I think for most of us it's just massively increased our time on water. I come from a wave/freestyle background and being light I could still get out on my freestyle board and cruise around on the 5.2 in >16kts or so. In summer on a good week I could get a few arvos after work and maybe a day or two on the weekend. Now with the foil if it's >8kts and lets face it there are a lot of days when it's 8-12kts we're good to go, I reckon id' average 5 session a week in summer. And good sessions too, not slogging around trying to get good waves which was often the norm.
There's also nothing quite like light wind foiling. With the race gear, which is my focus, once it's 12kts i'm just fighting to control the power and going such speeds in such little wind is just awesome. At 10kts or so on race gear you're already going ~23kts on hot angles, the apparent wind is quite addictive
I basically only sail the waves now if the surf or wind is firing. Since I have race foil gear once it's mid to high 20's it's a bit out of control so I might do a bit of high wind training here or there but more likely bust out the freestyle kit, good to keep sharp across all disciplines as the compliment each other.