Title, basically. Some other details: Two different but important facets of problem solving are a) broadening your search space in the first place and b) knowing how to "prune" and abandon ideas that lead to nowhere.
If you could help me find this, I'd really appreciate it! I've been looking for this for so long
Maybe you mean this? https://mzhang2021.github.io/cp-blog/difficulty/. It even has tree/pruning diagrams just like you wanted.
Yes! It is exactly this. Thank you so much!