I've found that matchups against strong zoners that seem hopeless at first become pretty winnable with a bar or two of trait. Often if I can get one bar, I'll mb wall, df2u, bf1, which often resets the pressure and they tend to under estimate your extra fast projectile. Often I end up forcing chars like blue beetle and cyborg to actually close with me instead of the other way around.
As far as the trait, I've found that in MUs where I don't need the projectile speed, I just don't bother with it and use db2 enders where I can mid screen.
MUs where I do, I build it and leave it, I almost never spend it, it's not worth giving them the ranged advantage back and having to build it up again.
I think I'd only spend it on a guaranteed corner reset, and only then if I was pretty sure they won't just clash out of it. Spending it to squeeze 100 extra dmg out of a midscreen seems like a waste to me.
Don't have much xp with Dr. Fate, doesn't seem to be a lot of em.