'Pends on the weapon involved.
Brass recovery varies by weapon. My SKS, for example, is the most enthusiastic thrower-all-over-the-place of brass you could imagine (it is a characteristic of the breed) and on a very good day I might get 90% of the brass back, but there's always that 2 or 3 which go straight up and literally disappear, it seems. If I reloaded steel cases there'd be plenty, but since brass is all I'll do, there is a constant drain on my supply of 7.62x39 cases.
My 1911 is almost as bad, though it doesn't throw the brass quite as far. Usualy I can find all of the little dears--and it doesn't really matter, anyhow, as there is always .45 auto brass for the scrounging. I've got as much of that as I can handle.
At pistol league, some of the guys use a brass catcher--most don't. Frankly, most of the brass catchers I've seen are pretty Rube Goldberg-ish, and I wonder if they aren't more trouble than just sweeping the brass up off the floor.
I'm hoping to get one of those M1 Carbines from CMP when they become available--have no idea how badly they toss brass.
My Mossberg 500's toss their hulls very sedately and predictably, almost in a pile--very easy to retrieve 100%.
The rest of my weapons are all break-actions, bolts, and revolvers. All 100% recovery of brass, at least at the range. When firing @ a live animal, frankly brass recovery is not one of my top priorities.