I have 13 bantams, but still don't seem to collect enough poop for my hope of perfect compost. I could use more. Maybe if they were standards, I'd have enough? But I thought, at first, that more than 10 would be "a lot". I was wrong.
They don't seem to take up ALL the space I have. There's plenty of room. And when I wander after them with my pooper scooper over the driveway, I only get half a scooper full after 3 days' worth of wanderpoopin.
Next, I'll be building a sandtray under their roosts, and using a kittylitter scooper to collect sandy poops which I'll mix with fine pine chips from the coop floor. Oh, yes, that's a plan. For more of these:
I would say 100 is a lot to me, but definitely not TOO MUCH. Over 200 would be a little more than I would want to take on. Not saying it will never happen. I really like to know my individual chickens. I like knowing their personalities and quirks. I might be able to keep a separate flock that would be for utility only (ie: eggs/meat). I really am not sure I would be able to take that on though.
I have 4 Silkies, and to me, they don't count as chickens!
I also have about 30 other Bantams, and I wouldn't mind rehoming a couple.
I currently have too many cockerels, so I may pair them up and sell them later.
But to answer the question, a lot is more than you can handle.
And I can handle about 30.