About 2 years ago, I tried cutting back my daily OP time from 20 minutes to 10 minutes. Within a week, the keratosis pilaris bumps on my face, thighs, buttocks and upper arms started coming back. I resumed the 20 min. duration, and the KP reduced. So not only is giving up OP altogether not a good idea, even doing it for less time isn't as effective.
I now do two 10-minute sessions back-to-back, changing the oil. I use either sesame or walnut for the first 10 minutes, and coconut for the second 10 minutes. I don't know if this really makes a difference, but things feel good.