Well I've been foiling for almost 2 years. The first 6 months allowed for reasonable progression as I was out most weeks.
Then a job/career change meant I wasn't able to kite mid week anymore. So I became a weekend warrior.
Splitting sessions foil and mutant on the weekend depending on conditions meant I might not foil for weeks at a time.
Over winter when the wind and weekend didn't line up there could be weeks at a time with no kiting at all and maybe foiling every 6-8 weeks.
As a result of the lack of water time, I'm forever consigned to the same skill level. I spend a most of the session getting back to where i was last session.
Then I don't progress any further. I'm constantly stuck in just being able to sometimes foil gybe and most of the time having to surface gybe.
I'm thinking if you want to be good this foiling game is for guys who can get out often and invest a lot of time practicing.
For the part-time occasional foiler progression is very difficult.