I struggle with this as well. I don't really scrunch out the crunch, and I just wait for the cast to wear off. I try to not use too much gel so I won't have the hard cast for too long.
Some people use a silk scarf to scrunch or a cotton t-shirt to avoid creating too much frizz. I did not use neither method, so I cannot testify.
I find that if I keep up with consistent deep conditioning weekly, and be as gentle as possible with my hair, I don't have as much issue retaining. But anytime I slack off or get lazy, I don't see much progress with it.