Magical ammunition, yes. Regular ammunition, absolutely not. Same with rations, rope, basically any non-magical adventuring equipment - if your character probably would've thought to bring it then just say you have it without tracking anything.
This is where I've largely fallen as well- but I do wonder about the implications, lines, slippery slopes and such.
Adventuring gear like rope. "Your character would've thought to have brought it, so don't worry about it."
What about antitoxin? "You knew you were going into a spider den, so your character would've thought to have brought it. You have it."
OK..
What about alchemist fire? "Your character is a seasoned adventurer, you run into swarms of things, trolls, etc. all the time so of course you'd have thought to bring some."
Again, I don't have them track mundane ammo- I occasionally go with the "it makes sense that your character would know/do that, yeah we can say that works," but it's interesting to think about how far one goes when serving the player skill/knowledge vs character skill/knowledge dynamic.
I remember Back In The Day "if it's not on your sheet, then you don't have it." But we've definitely moved away from that...
So is this move more of the "simulationist vs gameist" play preferences/design?
I guess this is a priority thing... what's more important: Player skill and responsibility, or "telling a story together."