Problem is lack of inventory space, you won't be able to carry ammo for every weapon you want without giving up others or even health items, and each slot is limited to the max you can carry, and there are quite a few bullet sponges in this game.
i would say just keep a good balance of melee and using ammo.
Careful what you say, mods can now delete posts based on what they think are insults rather then actual fact based insults, Terrible system at it's finest.
I just finished chapter 1 and my guns were pretty much loaded to the brim the entire time. I even had make herbs to make room for more ammo.
Of course i was going for headshots and was shooting in singles.
For the most part (in all campaigns,) ammo as a whole is common. However, each ammo for each individual weapon can end up being a little scarce (assuming you don't get the ammo Skills.) You should almost never run out of ammo, but you may need to end up using a gun you don't want to.