They seem to be very generous... Would it make a difference if I didn't pick up things so I can get them later? I had one game where I had 3 max ammo sitting in front of me. It just made me
all over the place
I'm not entirely certain, but I don't think it works that way. Grab the Power-Up or don't, either way the game counts it as dropped, and therefore lessening the amount you'll get at higher rounds.
I agree that the drop rate is accelerated for CotD. Sometimes we'll get 2-3 Power-Ups in the first round alone, and over a dozen by round 5.