[cwsand]

Yeah, the shortcut would be Beat Detective. I'll usually map the tempo out at intervals of 8 bars or maybe the start of a section (verse, chorus, bridge) and use BD to map each section. Then I'll listen and look at the grid to make sure everything is right, and if not you can undo, fix the beat markers and redo it. Usually works well but there are almost always corrections to be made.

I know all about those old drum machine tracks and the fluctuating tempos - kinda crazy though some of it could be attributed to inconsistent tape speeds I suppose!