People who have mastered some pursuit will often consider their knowledge inadequate vs what remains for them to learn.
There was a time I was quite well informed about RS232 serial ports and the flavors of things that connected to computers using them; but that was long ago and I have mercifully forgotten most of that. Did you know the standard specifies backup signals? There were the occasional items that used some of those lines. They were robust early GPIO and if you were lucky you might even find a interface cards where the RI line could trigger an interrupt.
I am good at "cutting things up"; be that carving foods with knives or trees with chainsaws. (Felling trees with knives is laborious, but possible: good practice to build up autonomic level muscle memory.) The real trick is to see how a thing is made, and where the stress points are most vulnerable to available tools. That skill serves many other applications. I can still learn new things from a tough roast or a wiry bramble patch.