I'm not 100% sure if the leaving it on for long period does anything for me or not. I don't regularly deep treat, but I'm trying to fade my hair color, so I figured maybe longer would help. Anyway, the heating pad felt good on my head. I don't have one of those heated caps. I just put my hair in the plastic shower cap and use a heating pad to warm it up.
I have one of those drying bonnets that you can hook to your blow dryer, but if you look in my Fotki, you can see why I don't like to use it. It falls over my eyes and it's noisey, too.