I play Dudley a lot, so yeah… It would be stupid not to use the ultra. Good damage and a bazillion ways to combo into it… mmmm…
Corkscrew Cross is also an awesome reaction punish against roll- or slide-happy Blankas and similar characters. I once caught a Dhalsim’s whiffed c.mp (or something) on reaction. That was exhilarating.
Depending on character I also use the ultra as a “panic button” in situations where I’m low on life and would be screwed anyway, such as after a whiffed ex mgb. Some people try to punish it with really slow moves.
And sometimes I just go “scrubby” and throw it out randomly (usually on wakeup) if my opponent seems aggressive. It doesn’t work that often but sometimes catches people who think they’ve already won and get careless.
(The above tactic gets me way too often still I’m not a very good player yet, but I’m learning. Recently I’ve been trying to learn footsies but I honestly have no idea how well I’m doing.)
Basically, the answers you’re going to get are going to be heavily dependent on what characters people are playing. The FADC/combo into Ultra is a big part of the gameplan for Rufus, Sagat, Ryu, Rog, Chun, etc. etc. etc. I play Blanka and Honda, and as a result, I tend to rely on footsies and shenanigans for my damage.
It’s fun to land the occasional cross up Blanka Ultra 1, or use Honda’s Ultra 1 as an anti air at JUST THE RIGHT TIME, but I can’t count on that every round.