I try not to walk my bike up hills, but I have a couple 10+ percent grades that are at least a half mile long on my regular route that I can't help but to dismount and walk up. Lately I've been doing a mixture of ride the first 1/4, walk 1/4, and ride the rest. It doesn't help that this particular road is extremely uneven.

Last weekend I did a 50+ mile ride, and on the last 5 miles I had one 10%-ish grade to climb and just couldn't do it, even in my lowest gear, so I ended up walking the entire thing, and coasted down the other side. This was after a day of many 8% grades, a badly developed section of a loose gravel trail, and many rolling hills.

Hills are a challenge but not nearly as bad as climbing a hill with a really strong headwind!