This week, I wrote down a number of shortcuts I use a lot (or just discovered and will use, when making this list).
It is, of course, far from exhaustive. For example, there is a shortcut for each painting mode (overlay, multiply, etc.), but IMO, it is too much to memorize, unless you use only a few of them frequently.
Another trick: in the above mentioned panel, you can do Save/Load > Export Scheme, and it will export the whole list in a textual format. Then a quick regex in a text editor will remove all those with =none, leaving only the assigned ones.