I am not in a band or record my stuff but I use scales as a guideline. Me ears weren't that great, so I needed to practice scales to hear the right and wrong notes. The scales give me a starting point. And when I do play with my acoustic buddies the theory allows me to do more fun stuff that sticking to the root notes fo the I-IV-V progressions they always use. I do dork out to theory a lot, because I enjoy learning the bigger picture of how music works, but I think you can trim it down to what is really useful to your own needs. Intervals, scales, modes, arpeggios/chords, understanding keys are the most important to me. Right now on guitar I am wanting to learn more than the basic common chords I always use, and what ones will work with overdrive, fuzz, and distrotion. When I get bored then I try to learn something new, like an exotic scale or chord that keeps it exciting for me.