Mastered as in I could teach it to others, and assemble many complicated rules for many complicated patterns.

I am always impressed with folks that retain it.

I would a ton of it for a month or two, and then do nothing with it again for more than a year or more.

It takes a lot for permanent burn-in for me. That’s the curse. The blessing is that I learn very quickly.

Waterfall: Spend 10 years compiling written functional and technical requirements. Cancel the program due to budget overrun.

Finite rules for perfectly sifting infinite options

I mastered and forgot almost entirely RegEx several times now

This stupid house initially had three water heaters. A. 110 volt little heater that only ran the kitchen sink and the dishwasher. A 55 gallon water heater to run one bathroom and the laundry. And a third 60 or 65 gallon water heater to run two bathrooms and that was it. Isn’t that crazy? I removed the 110 volt water heater and the 60 gallon water heater, and now I need to replace the 55 with a heat pump water heater. This is probably something worth doing. It should consume a lot less electricity and I intend to disable the resistance heater for it. I will get more capacity to help.

That stupid 55 gallon water heater is framed into a wall, which is patently insane.

I wish you luck and I would strongly suspect the water heater is your culprit.