I never worry about the powers that give a more accurate system of reference to even hundred yd. intervals with whatever reticle i'm using. I just establish a system for the highest power and go with it (especially with reticles like this 22 Long Rifle system-- http://www.rapidreticle.com/22lr3-9x32.htm
. that i have on an AR-15 that's not even close to matching it's trajectory, or mil-dot reticles). Interpolating between stadia is more accurate than most give it credit for. I've proven this several times with inexperienced shooters. I never have to look up at the optic to see what power it's on. Once the system's established, the dope goes into a Butler Creek scope cap cover, and all i need to do to quickly reference or rereference bullet impact is just glance up to the dope and back to the ocular for my info. No getting out of position to dial or redial, just have to look up then down. Most of the time i don't even have to reacquire the tgt., as with very little practice the FOV doesn't even change. This system has proven itself many times now in the field hunting.