In my previous post, I wrote about why D&D shouldn't be seen as a half-day hobby and instead ought to be seen as a 2-hour board game. To many people, the idea of a 2 hour game is baffling, either because they grew up playing in 8 hour sessions as kids with nothing better to do, or because they're used to the half-social and half-game model of home games. I run a 2-hour game pretty regularly, at home, weekly at a local café, and with co-workers when I travel for work. Here are some best-practices I've managed to define from experience.
In 2 hours, you can generally expect to get through three rooms of a dungeon, or three encounters in an adventure. That's about 40 minutes per unit. If you plan for more than that, then your game isn't going to be 2 hours or else you're not going to get through everything you planned.
In the unlikely event that you find yourself running desperately short on material, you can always throw in an extra encounter, or else end the game early. This has never happened to me, so I don't think it's a likely scenario.
If everyone involved is familiar with the Player's Handbook (5e) or Core Rulebook (3.5 Pathfinder), then you can build characters as a 15-minute lead-up to the 2-hour game (but then it's a 2.25 hour game). Otherwise, keep a stash of pregenerated characters on hand. One per actual class is nice, but sometimes overwhelming (it's hard to distinguish between a druid, wizard, sorcerer, and warlock in a 2-hour game). One per general archetype is fine: a thief (rogue), a fighter (paladin, for the benefit of healing), a monk, a ranger, and a spellcaster.
A level 1 character has the benefit of being easy to play because there are fewer special abilities to track. However, they do tend to be pretty boring to play because they're weak. Build level 3 pregenerated characters instead. They're still simple to play, but have most of the classic abilities associated with each class. Instead of writing lots of text on the character sheet describing each ability or feature, use keywords that remind experienced players of what the class can do, and prompts new players to ask for more information.
Some dungeon masters like to roll dice in secret. I never do this because I don't particularly believe it's fair, but I also don't do it because in a 2-hour game especially, the DM dice roll is an important part of the game. If you hide your dice rolls so you don't have to kill off a character when it's inconvenient, then nobody is ever going to die within 2 hours, ever. Roll your die out in the open, and if a character falls swap it out with another pregenerated character. Nobody would play a board game in which all lose conditions were deactivated, so don't play D&D that way. If you feel the need to "rescue" a character from a premature death, use Inspiration.
Wizards of the Coast says Inspiration is a reward for "playing your character in a way that's true to [your] personality traits, ideal, bond, and flaw" and that a "DM can choose to give you inspiration for a variety of reasons" (PHB p125). This is a DM's get-out-of-jail-free card. If you don't want to accidentally kill characters, reward Inspiration liberally so your players can spend Inspiration to re-roll the failed save or death saving throw that would otherwise kill them.
Remind players that they can also reward each other. Once one player has Inspiration, that player can give it away to another player in dire need (PHB p125).
I handle Inspiration in two different ways, depending on how players respond. Initially, I hand it out any time a player prays to their god. This seems like an obvious in-world reason for gaining Inspiration, and it satisfies the PHB's stated intent (praying to an imaginary god is in line with a fictional character's traits, ideals, and bonds). This often inspires other players to follow suit, so everyone can get Inspiration quickly. I also award Inspiration when a player does something particularly special in a game or, in the case of a slightly troublesome player, as positive reinforcement when they conform pleasantly to the table culture.
I use Inspiration in Pathfinder, as well, because it's such a useful mechanic.
Regardless of how or why a player gains Inspiration, I remind them of Inspiration in trying times of death saving throws or failed checks that could result in massive damage. For me, Inspiration is exclusively the system that allows me to roll dice in the open without also crushing a person's hopes and dreams when they're truly invested in a character. Some players don't care about their character, but others do. Inspiration gives the people who care a way to stay alive, without spoiling the anxiety of the game through secret DM dice rolls.
This doesn't work with new players, but for experience players it's useful. When possible, roll the attack (d20) and the damage (d6 or d8 or d10 or whatever) at the same time. If an attack hits, then the damage is applied. Otherwise, it's ignored.
This can be a difficult habit to get into, but it can be a huge time saver. It doesn't actually save that much time in terms of actual dice rolling, but it forces players to think about their whole attack in advance. Instead of starting their turn pondering what to do next, a player who knows they need to roll both an attack and damage tends to spend the round leading up to their turn investigating what damage die they need to have on hand. That means they're ready to roll when it's their turn, and all the information required to resolve the interaction is immediately available.
Rolling an attack and damage together does not mean that a player can't ask for more information before executing an attack. Not every turn has to start with a silent attack roll. Players can ask for more information and ponder the best action, but at least rolling the damage with the attack eliminates this common back-and-forth scenario:
DM: "OK, you hit. What's the damage?"
We've all had that conversation as both the DM and the player. Instead of having that conversation several times per game, empower the player to have it internally or quietly with another player before their turn begins.
No question about it, though, this is a hard one to ingrain. It's just more natural to attack, confirm, and then roll damage. And that's a lot easier to follow for new players. That said, if the DM leads by example and encourages experienced players to do it themselves, it becomes a little time-saving trick you can use when convenient (and I gladly forsake it if any player is having a difficult time following along).
Start your game at exactly the time you said it was going to start, not a minute later. It's acceptable to start early if everyone's ready, but by no means start late. If a conversation is happening, cut it short when the time arrives.
Furthermore, mark the mid-way point with an alarm on your phone or watch. It helps keep you on track, and players start to pick up on it themselves. There are only 2 hours to play, so if focus starts to dwindle 45 minutes into the game, it's quickly restored by an alarm subtly reminding everyone that the game's half over.
The tail end of this is true, too. End on time. This is tricky, because everyone may be convinced that the game shouldn't end. Or at least, that's how you'll be tempted to interpret their body language. But it's better to be true to your word. If you advertised a 2-hour game, then make it a 2 hours. If players want more, they can vote to override you, or come back for more next time. If you don't end on time, then people will catch on and they'll know that when you say "a quick 2 hour game of D&D" you're lying.
End on time.
Having a game in the place where you live seems like an obvious and easy choice. It's cheap, it's well-stocked, it's comfortable and familiar. However, sometimes it can be the source of problems for a gaming group.
Sometimes, a home game feels too casual. For guests, it's easier to "forget" to show up to a friend's home than it is to "forget" to show up to a meeting in a public place like a library, game store, or game café. It just somehow feels like a different kind of commitment to most people. For hosts, it's easy to cancel an event at home because you forgot to clean or your partner worked a late shift and needs to nap.
Separating your game from real life is sometimes the thing you need to do to make sure it happens on a regular basis.
Everyone knows that arguing over rules takes up time, and in a 2-hour game you literally do not have time for that. When questions arise over a specific rule, move on quickly, no matter what. Make a ruling, acknowledge that you'll have to look it up for "next time" (whenever that is), and then move on.
All of my advice is based on my experience and the people I play D&D with. What works for you might be a little different. The important thing is to find time for the game you love, and don't let expectations about how much time is meaningful take anything away from your ability to enjoy D&D.