I'm wondering if anyone regularly rolls gliders
down a cliff for launch.

I was thinking that a suitable slope off the edge of a cliff
would work just as well as any tow/winch/auto/bungee/rotax.
And if there is reliable lift nearby, you can come back and
land.

I know this is commonly done with hang gliders, but haven't
heard of a location that does this with gliders. Maybe somewhere
in the Sierras or Alps or something like that? Any of you
Europeans heard of something like this regularly used for gliders?
I'm thinking of a place where you launch, then find lift, do some
circles, and then come back and land.