The PWP trick 'works' by generating 'surprised' emotions from villagers by spending time away from them.
I just got the illuminated tree suggestion a few minutes ago, and it went something like this:
- I jump into the ocean, and stayed idle for about 8-10 minutes. (Don't mind the jellyfish stings.)
- I catch something from the ocean.
- I walk in front of every villager to see if they have the emotion.
- (If I don't get a suggestion, I start again)
This isn't a surefire method to get PWP suggestions though. It just ensures the villagers have a 'surprised' emotion.