If you have something that you think has general and lasting usefulness -- to the extent that you would maintain it over time -- put it in Code Catacombs, no matter what length it is.

If it's a nifty trick that saves you some lines of code in one or more situtations, it's probably a good snippet.

In either case, you'll probably get some critiques -- which, no matter how they are phrased, will really be constructive for you (so don't be offended -- the same has happened to everyone who has contributed here). But note that you can update your root node in the catacombs, whereas it may be harder to do that in other sections of the monastery.