I have code completion in vim and I try it every few years and sure it can save a few key strokes but the habit of using it never stays with me.

I think I just learn the code base and build a mental model of where everything is and it works for me. I spend more time thinking about how to organize my code well than to actually type it in my editor anyway. It probably helps that I'm working on Rails apps so there are strong conventions about how to do things that makes this easier.