I have no "musts" regarding hill climbs. ("You must sit" or "you must stand".) But I stand a lot. Always have. I love the dance. I can ride out of the saddle nearly as efficiently as sitting (as long as wind resistance isn't a factor). I ride a lot of fix gear so I do a lot of hills where sitting isn't an option. Now, on steeper fix gear climbs, my hands and esp forearms feel it, but pulling, not pushing. It hurt to touch my forearms with soap showering after the 2014 Cycle Oregon Day 4 climb hitting 14%. (See my loge. That photo was taken at the steepest point.)

Ben