I throw my Bars almost instantly, but I hold onto bar spins for a long time, so I almost pass the bar around, so I really never release off the bars...
Oh! When I first tried doing them, for the first few days I would get like 270 and then My scoot would slam into the ground... I just constantly practiced it everyday for like a week, and eventually I just started catching them like everytime.
Moral of the story, Practice, practice, practice.