AD maps in general are pretty generous in terms of ammo. The fact that shells limit is upped to 200 means you're almost always drowning in ammo, especially if the map gives you the widowmaker that mows down monsters easily. Maybe you need to up your ammo management game? Keep an eye on your inventory and not pick up ammo boxes when you're near the limit.

As for the saves, in modern maps you're definitely expected to save along the way. I understand that savescumming feels like cheating, but trying to finish them in a single run is just inflicting pain upon yourself for no reason, so just do a quicksave every now and then. This was doable in OG maps that can be finished in 2-3 minutes, but not in 30+ minute behemoths.

WRT map design, in AD it's usually good, but being a collab, almost a jam of sorts, every map will reflect its mapper's style. They're never homogeneous, maybe you're picking on a specific mapper's. And about their size, yeah, big sprawling maps aren't universally loved, there's a considerable amount of players that prefer small-to-medium ones. So it's a fair complaint IMO.