For me, as a GM, I cannot keep track of this stuff mid-game. I don't want to be in combat and mark off arrows shot by a player; I have my own monsters to track. However, I can ask about it during character creation. I review character sheets. If they list 140 pounds of gear and still list their move speed as 30' I'm going to question that.

If they have no food or water in their gear, I'm not going to let them retcon buying rations. They're just stuck in the forest now, and they better have the survival skill to forage or hunt food. Or bum it off another character who bought too much.

But after that point? No. We're now 4 levels in, and you have a Bag of Holding or a Handy Haversack? Weight doesn't matter.

At level 1 you only bought 20 arrows and you never re-purchased them? You're definitely going to run out. But at level 6 you now have a never-ending supply, so why bother tracking it?

Here's how I determine if it's worth nitpicking:

• If I ask them about it, will they shrug and make some adjustments and solve the problem? Then I shouldn't care.
• If I ask them about it, will they say "Oh, I forgot, can we retcon that?" In that case, yeah, I care, because you clearly need it but have no fallback.

At level 1, asking about rations is not only realistic, but it pushes players into a real challenge that should be part of the game: how do you spend your extremely limited starting funds? That test is part of surviving the early stages of a campaign. It matters.

At level 8, any mundane thing you can bug them about they can solve with a sigh and a spell. Water? "Oh are you kidding me, GM? Fine, cleric creates water. Happy?" Food? Same thing. Carry weight? Magical bags and containers, and horses, and animal companions, and a barbarian with a strength of 26 before raging -- it's ridiculous to think you can challenge them on weight issues at that level.

I mean, you can bring it up, but there is no way to make it be an actual issue. They will solve it, and they won't need a trip back to town to do it. So at that point, it's just wasting game time. Besides, at higher levels, you should feel more powerful by way of more powerful challenges. Instead of worrying about food, you might worry about... I don't know... if a kingdom is going to fall, or if a squad of paladins chasing at your heels will catch you and take you out, or if the goddess of time has locked you in a time loop, or whatever else. You should be worrying about plane-hopping, not whether you have 1 or 100 arrows.