Making a second game is not to prevent burnout, on the contrary it only helps it, you have 2 times the pressure. It can help to prevent weariness though, but I don't recommend it. Do you have an example of a dev making multiple games and finishing them?
Sorry, was this directed at me? You never quoted anyone, so it's a bit hard to tell. You only have "2 times the pressure" if you plan to do something with the second game. I had thought the second thing was only a
temporary distraction to create without stressing about this game, with the idea to come back to this at some point. If it was intended to be a second full project that would continue simultaneously with this one, obviously that's a mistake. In any case, the effort to shift for a bit doesn't seem to have helped anyway.
FYI, weariness can lead to burnout, so I have no idea how
temporarily shifting to another project to relieve weariness would
not potentially help prevent burnout. Now, if the dev hadn't intended to make the shift in focus temporary, that's another matter entirely. I have no idea what's going on with this dev (as I've said multiple times now).