Somewhat related to the OP's question is the "20" or so pool skills. When many talk about polishing their dive skills they are referring to some basics like buoyancy, dive planning (profile, etc.), navigation, buddy stuff, etc. Don't forget the stuff you did in the pool--like reg retrieval, breathing from a free flow, removing/replacing unit, disconnecting LPI hose, even CESA (though some advise against practicing that). Air share ascent, the tows--all that stuff that I didn't give a thought to for 4 years until taking the DM course. These should be reviewed somewhat regularly. In my case, being almost always diving solo due to my location, I practice some of them now and again--the ones not requiring a buddy. But once weekly I go over my list of the 20 and mimmick doing them while sitting in my chair. Better than nothing, and you never know if you'll ever have to use one of them. I did once have to take off my unit and shove it up on rocks in nasty surf. I did once have an inflator stuck inflating my BC and had to detach it (continued the dive orally inflating, another of the "20" skills).
The only skill I had any real trouble with was the unit on/off thing. The rest-- I just ticked them off easy. So it was natural to not even think about them and just start diving. You have to practice mask clearing because you'll have to do it anyway. Not a good idea to neglect the skills like I did.