I'm erratic when I'm caping elites.
My Rit is going for the cap title, and now has 3 left in Tyria, but like 100 to go in Factions and 100 in Nightfall.
I went for the most caps in the area. Perdition Rock, 3 signets of capture and go hunting. Kill everything can cap 2 or 3 skills (if the 3 bosses spawn). 1 Trip, 2 or 3 elites capped. Easy.
I try to go for the random spawning bosses first, as if I'm lucky I will get the boss, otherwise, I'll eventually give up and go else where. That is where I'm at now... Abaddon's Mouth (Soul Leach, Restore Conditions are the 2 I'm missing and they are random bosses - spiders in the bonus area).
Going for the sure thing can be done later, as you know they will always be there, and you don't have to get board waiting for it to show.