I've always done 20, 30 and 40 for whitetail hunting... with the 20 being green, 30 in yellow and the 40 in red. I've explained it on here before, but the thought process goes like this...

Green (20 and under)... you've got the green light! Let 'er rip!!

Yellow (30 yards).. Let's think this one through for one second... Will the animal come closer? If not, be careful, and take good aim.

Red (40 yards)... Whoah! Wait a sec here... Do you really want to take this shot? Is it the best you're likely to get?

Red also "winks out" on me the quickest in failing light, and I figure if I can't see my 40-yard pin clearly enough, I don't need to be taking that long a shot. Yellow goes for me next, leaving me with a bright green dot to shoot anything up close at the last legal shooting minute.

I've since added a fourth pin to my rigs, due to my Colorado elk trips which I'm starting to take now...

I did just re-order a new retro wrap kit for one of my older Hunter Hogg-Its that's going on my brand new Allegiance though... it's going to be a .29 green, a .19 yellow, a .19 green and a fourth .19 yellow. I got in the same sight configuration a couple days ago with .19, .10, .10 and .10, but decided that while .10 is great for 3d, it just wasnt' going to cut it with my eyes for hunting, so I sent it back to have it re-done.