I have some maternal lines that are just always retarded.. always try and duck around a gate, etc.. thankfully most of those are gone... Other maternal lines, you put a halter on them, they fight for 5 minutes the first time, and after that they settle down and they're good from then on in. Some people do just love a good rodeo, I see it in my neighbor's herd.. The old man always was calm with his cows, walked among them, everything was fine.. since he passed, his sons are pizz poor cattlemen as far as handling, only time they get worked is for shots or something else they don't like, so now they scatter when someone comes along.
On the percentage of bull calves you keep intact, well.. if you have a really exceptional herd you will definitely keep more of them as bulls if you have the market, but everything is always on a bell curve, even if all your animals are good I don't think it's a good idea to keep everything intact, that's not how you make progress, that's how you stand still... Then there's the definition of what you think is great, which might not match someone else's definition, apart from the evident stuff like basic functionality.
It's been 6 years since I've kept a bull calf intact, so about 1% of my calves get to keep their nuts at birth.. I kept one for a year then decided I didn't like him and he got shipped.. Same momma as 2 previous bulls, but her and that Limo sire just really didn't 'nick', she had home runs every time with the other bull so I thought I'd take my chances.. oops, didn't work!