You'd need to better define hills with gradient and length. Climbing mountains for 10, 20 or 30 miles continuously is nothing like climbing a hill.

On rolling terrain, I might run 90-110 rpm, but on long climbs I find 80's to low 90's to be the most efficient. If the climb gets steep enough, you won't find many who have low enough gear to reach 80. I used to run a 53/39/28 with a 12-25 and I've spun by a lot of under-geared riders over a 4 seasons in the mountains. These days, I'm using a 50/34 with a 11-25. I lost my lowest two gears, but I'd rather stand on the few steep sections where I'm slighly undergeared, than have two gears I seldom use.