DND_Reborn
The High Aldwin
Well of course, but that is a person's choice. If a fighter retires and doing keep up a training program or something, he won't improve and most certainly will decline. Now there is a finite capacity, as new things become important old things suffer. So yeah I get that most people who could do algebra in middle school or high school would struggle with it 20 years later as adults trying to help their own kids.Simply because pretty much any finely-honed skill or ability deteriorates somewhat if not used for a while, and may or may not fully come back if re-started.
Physically, people let their condition go. Mentally, they lose focus and think of other things.
There's no game mechanics to reflect this, however.
With the new UA there is in a fashion. The different versatility features allow for PCs to exchange a spell or skill out for a new one.
In AD&D, there fortunately was aging rules that would reflect declining physical conditioning, etc.
IMO one of the lacking aspects of 5E is that characters don't live outside of the adventure. Will most games see a character live out decades of their life while occasionally going on adventures? Not IME. More's the pity.