So I arrive at the track, and see that there is someone walking in lane 1 and someone jogging in lane 4. Cool, I'll do my workout in lane 3. Except half way through the first repeat, the person who was in lane 4 is now in my lane. No big deal, I'll just pass her, then move to lane 2 for the rest of my workout since lane 3 is now occupied. Oh, but now that I'm part way through my second repeat, it appears that the lane 1 walker is now in lane 2. No problem, guess I'll use lane 1 now. But now lane 2 and lane 3 person have made friends and they're walking together taking up lanes 1-3. Alright, I'll give myself plenty of room and move all the way out to lane 8. But now lane 1 walker is no longer chatting with her friend, and has decided to walk in lane 8 for a while just for a change of scenery.
Is it that hard to pick a lane and stay in it? This isn't really even a matter of track etiquette. It's just something that comes naturally to most people who aren't drunk (or dodging meandering walkers/joggers).