It's definitely much faster to use the cheese spots for Sepiks, Valus, and Aksor. It's a bad idea on Phogoth because it spawns extra adds, but I would say it's neutral for Sekrion and Omnigul. The Sekrion cheese spots let you avoid some adds, but it doesn't make a big difference in completion time. For omnigul I guess it depends which room you use. You can get bogged down in the entry room for a long time, and the boss room is kind of a cluster-blam!- so you're going to have to hide in there to get your shields back eventually, which isn't too different from just going up to that room thing and reviving your teammates.