i wash my hair every 2 - 3 days, and i'm relaxed, but i airdry 90% of the time, so it's not straight.
but when my hair IS straight, sometimes i'll sit under the dryer and dry-rollerset my hair with heat for a couple of minutes... like 3 or 4 times a week.
i think a hooded dryer would be fine to use on your hair anytime, because it's not direct heat. just make sure that your hair's been properly moisturized, and you should be good to go.