I'm 29 and started focusing on park when I was 16 or 17. I think from a park standpoint I peaked around age 21 or 22 in terms of being willing to send/learn new stuff and having my biggest bag of tricks. I still ski hard but it's like 70% out of the park 30% in the park. A big part of that is after I moved away from PA after college, all of my friends that ripped park were still there, and the people I did ski with from then on weren't into park really at all, so I'd be making laps solo if we were all out together. I think outside of the park I'm still progressing and skiing close to my own personal highest level.
I spent a lot of time at Copper this season and there were a lot of days where I didn't touch the park once because the snow was good, and instead I was finding drops/steeps, skiing trees/moguls etc. The days I did hit their parks up though I still had a ton of fun and love riding park to this day, it's just different.
When I do ski park now I'm really only doing stuff that I know I'm going to land no problem and I focus on just being as clean and smooth as I can be. I haven't spun over a 5 in a few years, and I almost never 2 on anymore, but I'll do a nice floaty grabbed 3 or 5 over a big jump any day and still enjoy hitting rails.