On shorter rides I try to avoid doing it, but on some of the longer brevets with nasty hills there hasn't been much of a choice for me. The hill to the finish line of the Baker Lake 400k is almost 1/3 mile at ~10%. After already riding for 252 miles there was no going straight up that sucker.
But I did manage to tackle Norway Hts. Hill (18%) without switchbacking at the end of the locally infamous quad buster, The Summits of Bothell which is 3750' in 40 miles.