I use a 15 psi gage.
~6 psi front and ~12 psi rear (I weigh 175#). I go on tarmac to go to the trails, but never adjust pressure forth and back since that tiny difference in rolling resistance is less than my pumping energy.
I assume you use higher pressure because of rolling resistance. I never noticed a difference. The resistance is because of the tread pattern, not how much pressure you have (within reason)