I dont do it myself, only short runs like 10km to say hi to other riders at other spots along the coast, and 10km upwind only takes maybe 45 minutes, and less when downwind, depending on gear and wind of course...
I think "distance runs" but in small circles like 3-5km is somewhat the thing all racers do "daily", or at least the days when out.
Yesterday when we had a good session, one of my mates saw on his GPS he had ridden over 100km.
Of course not from a to b, but 100km riding corresponds to about 65km if you went upwind and maybe 75 if downwind, so would be easy to do from a to b if you wanted.
The thing is it is really really easy and relaxing on a hydrofoil, so the almost perfect tool for this because you dont get tired but can stand relaxed on both feet on any course, apart from having a much wider windrange than other boards
You can also choose to make it a good workout instead, pushing to the max with a big racekite, so your legs will get an awesome workout and "burn" - or you can ride totally relaxed with the same kite upwind too, if not pushing it - amazing you can choose and find the level you like.
Riding the board down on the water would be totally stupid, as way too hard physically, and difficult, so never an option.
The only downside is if the wind drops totally - here a windfoil is way way better and would be my choice if I went quite far on open water distance runs particularly, thus the kitefoil is only the secondbest regarding safety/dropping wind, but not as good in low wind
For long distance runs along the coast the kite hydrofoil is maybe the best tool though, and you can ride "forever" when out there, you get so much ground covered under your feet in a jiffy