The ‘recently used’ is quite good but feels a bit capricious to me (eg I’m more often hoping that something is there than finding it)
It might be nice to have a ‘favourites’ category of both Procedures & Operators, like Steam games that you add to Favourites.
This might greatly help with friction of working with a handful of items regularly.
What it might look like: An outlined but empty heart icon? Or simply right click>Add to favourites. A category at the top of both Procs/Ops where favourites are kept.
Perhaps an empty category header could be displayed even when none are there, to indicate the feature to the user.