Being in an unusual position or situation can lead to a lucid dream because it increases your awareness. In an uncomfortable or unfamiliar position (like sleeping on a couch or in a hotel) your instinct is to be more aware for danger or pain. In my experience, this is usually a DILD technique more so than WILD. The usual advice to be comfortable during WILD is because you need to let yourself fall asleep. In your case, the long walk to make you exhausted might be enough to overcome the discomfort and get you to sleep regardless. So you've succeeded in combining several less common factors into a successful technique.

Why hasn't a more typical approach worked for you? Hard to say. And it's nothing to worry about. With WILD, I think it's hard to measure progress compared to DILD. With WILD it seems like you can try a million times with no progress and then suddenly something clicks and it starts working out of nowhere. Meanwhile, with DILD, there's usually some gradual development: better recall, more vivid dreams, some semi-lucid experiences, and so on. So with WILD, when you find what works for you, cool, stick with it. You can still benefit by experimenting and testing what other people suggest. In the end though, your own experience is the best teacher.