While reading the Monster Manual, I came across
A monster carries enough ammunition to make its ranged attacks . You can assume that a monster has 2d4 pieces of ammunition for a thrown weapon attack, and 2d10 pieces of ammunition for a projectile weapon such as a bow or crossbow.
So, first and foremost, ammunition for thrown weapons are just... more weapons? E.g., carrying 5 daggers?
Does this imply that a monster is supposed to carry (on average) 5 hand-axes (or some other thrown weapon) to throw away at PCs? It seems to me that this makes battlefield scavenging much more lucrative than I was assuming, and it also seems kinda silly for some creatures. I don't imagine a host of bandits to each carry 5 javelins on their backs, a greatsword, and a longbow as they move around.
I know that I can adjust them and not make them carry such weapons when the occasion isn't appropriate. However, is my interpretation of the rule correct? Are monsters meant to carry around 5 of each thrown weapon they have?