Recently, my long ones have been about an hour, average ones 15 minutes, and short ones about 5 minutes. When I first started out, they were terribly short, though, and I still have some 10 second ones nowadays.
This is the best technique that I’ve found for prolonging dreams (spinning and hand rubbing don’t work nearly as well for me).
It didn’t take too long for me to have some decent-length ones, maybe a couple months. And a lot of the short ones are my own fault…
…if you know what I mean. 