I have over 700h on the discus. I think it’s 98% gliding of all flights. In all the time I met two or three other gliders. So indeed very rare.
Today I had a flight 2,5h in the Andes. Startet in a hight of about 3900m total height 6800m.
Very impressive and exciting. Of course you have to try to find the best path for the route, but that’s why you have to study the landscape intensively and then memorise it well as you fly slowly over it
Love it 
Regards Ralf.