On my road bikes and mnt bike I can ride for a long time no hands. On my old Cannondale 3.0 crit frame, very twitchy and harder to ride no handed. My tri bike is also very difficult to ride no handed but is easy to control with a light touch. My fixie pulls to one side and it also difficult to ride no hands, so I'd say it depends alot on the bike not just your skill level.

that said, practice doing it will help just as riding on rollers gets easier with practice. Balance is a skill like anyother and should be practiced.