In a previous post, I wrote about how tracking encumbrance made loot more "valuable" by enforcing a weight-based economy. However, tracking encumbrance can be hard. In theory, it's exclusively the responsibility of each player, but if the game master (GM) doesn't announce the weight of each item then a player can't accurately track weight. And anyway, if no one's ever checking to see whether the weight limits have been exceeded, then is there really a weight limit?
Here are some of the ways I've helped weight limits matter in games.
Assign a party treasurer. It's this player's job to track each member's items.
When I've used this method, the player who ends up as treasurer is often the one who actually cares about in-game accounting. It's the person who enjoys tracking weight and rations and who's got what. Because of this, I've never felt compelled to audit the spreadsheet as the game master.
Create a shared spreadsheet using Ethercalc or similar. Players maintain their own inventory, and the game master can audit.
I like to be able to audit the party inventory not to make sure everyone's playing "honestly." Instead, it helps me prepare the game. When I know what player characters have in their inventory, I can create opportunities for them to get good use out of the items they have.
As a game master, if you want your players to track weight, then you must provide the weight of each item a character picks up. Frustratingly, D&D rarely provides the weight of loot in a module, which means you have to turn to the Equipment chapter of the Player's Handbook, cross-reference the item, and provide the weight. It's frankly a lot of work and can slow the game down.
This is why it's often nice to have a party secretary. A party secretary is in charge of looking stuff up while the treasurer enters items into inventory. This gives the party something to do while looting a corpse or a hoard, which is nice for the game master because that means there's suddenly time to read ahead and prepare for the next encounter.
However, Starfinder elegantly abstracts weight to "bulk." An item is either 1 bulk or some fraction of a bulk, and in my experience Starfinder modules reliably provide the weight of loot in bulk, making it easy to tell players what the characters have found and how much it weighs.
Erasing and re-filling in the inventory list on a character sheet can get messy. For my in-person games, I've used a system where I deal cards to players to represent items. I'm not talking about special item cards, I just use standard poker cards. Here's how the system works.
The number 20 is adjustable, of course. You can make it 10 or 30 or whatever you want. And you can make it different for each character, depending on that character's strength stat. You could have a base number of 10 for everyone, with each positive modifier representing +5 cards.
You could also make red cards represent small items and black cards represent big items, and you could allow a player to hold 15 red cards but only 5 black cards.
In this system, the weight is obviously being abstracted.
The point is, you use some real life supplement to help players track resources.
For me, the weight of items isn't as important as the number of items. I've never had a player try to argue that their character could realistically carry a horse, for instance, so the question isn't the weight of a single item but how many items there are. I don't care whether a character has 19 longswords and 1 ration, or 1 longsword and 19 rations, just so long as they don't have more than their requisite 20 (or whatever number you choose) items.
I realise that this isn't realistic. Probably it would be really hard to carry around 19 longswords. They'd be heavy and unwieldy. So would 19 rations. But I just don't care. It's a world where magic and gods exist, so I'm willing to suspend disbelief about an adventurer carrying awkward amounts of items.
All I'm interested in is imposing a limit to encourage significant decision-making. In other words, the "weight" limit is a numbers limit, and one way to enforce that is to allow characters to carry around a number of items equal to the number of available blank lines on an inventory sheet. If you want to set the carry limit to 20 items, then give players an inventory sheet with 20 blank lines on it. When they go to add a new item to their inventory and find that all lines are populated, it means they have to get rid of one item.
You can manually override the "weight" of an item by giving a player permission to group certain items together. A bag of 100 caltrops is obviously a single-line item, not 100. Arrows go into a quiver. Maybe you rule that "rations" (plural) is actually a singular stash of bulk food, and therefore belongs on one line.
Speaking of rations, it's sometimes important to track rations. In my experience, the "right" way to track rations is to first track time. If you're tracking time in your game, then you can confidently tell players when to deduct a ration from their inventory.
I've tried tying rations to long rests, but at least in my games long rests happen essentially between sessions, and as a group we rarely remember to perform administrative tasks around them.
It's been much easier for me to just track game time, and to announce when 16 hours have passed.
Lots of people have come up with lots of systems for tracking inventory. You might have to "shop around" before you find the right system for you, and it might change depending on your group. The important thing is to track inventory, and to track encumbrance, and see what effect it has on your game.