Rides with short, steep climbs are actually easier for me...the type of climbs that I'm riding above threshold for 5-20 minutes. I'm the type of rider with a good "VO2max" type power, with repeatability. The rides with big, long climbs are the ones that wear me down. There are several climbs that I ride semi-regularly, 3000-3500' of gain and take roughly an hour to climb. Doing 2 of those climbs in one ride feels considerably more difficult, to me, than doing a ride with 6000' of punchy climbing.