When I walk from Mile End Road to Sainsbury's, I almost always walk in through the front entrance. When I leave, I leave by the side entrance. This despite the fact that I walk past the side entrance on the way in.
When I walk into university, I usually do so via Mile End Road and the little bridge you can just about make out on the map. When I walk home from university, I do so via Hamlet's Way and (sometimes) the park.
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As you can see, there is little to choose between these two alternatives in terms of distance (actually, there's probably more to choose between them than I would have guessed - the park seems to win quite clearly) but it seems that there is a pretty regular bias that makes me choose one in one direction and one in the other. There are several other places where I've noticed this phenomenon.
Now, I know that there are lots of situations in which the fastest way from A to B is not the fastest way from B to A, even when walking, but I pretty sure this doesn't explain what's going on here. There's some sort of heuristic governing my decisions, and I can't quite work out what it is. It seems to be something like "if you know you need to turn, do so early". Why am I doing this? Does anyone else do the same thing? Have other, more bizarre heuristics?