I got it the same way, relatively stagnant but not because of too little time on the water
There are some basic reasons why one dont progress:
1. Way too little time on the water.
2. Not over-talented, and you reach your own limit at some point and you feel stagnant.
3. Not trying new things, meaning no progression.
4. Not riding with others, so you dont share nor get any "real life" motivation and input for progression.
5. You learn slow, maybe older, so it feels like you dont progress.
I am in #2 and #5.
Got loads of experience and good/talented in waves on both waveboards and hydrofoils.
But I can not do the "smart" things many can do, I simply got a physical limit that is hard to get beyond, in terms of moving my body, like some agile skateboarders and similar can.
Some can do these "magic" tricks quite fast and easy, not even having much time on the water, so very personal what YOU can do.
I know it is like that, so I just keep pushing trying new things, and also doing things I love and CAN do well to get some confidence ha haa.
Progressing very slowly now, and sometimes I have a day where I go "backwards" - but so many years have taught me to still enjoy these as it is how it is - a sport that is so dependant on complex skills that can change instantly with a blink of an eye - so no problems with that