g I don't care to put any more time in for 15s flights.
a glider specialist that says he has gotten 30min flights out of it.
The difference is catching thermals. Requires the right conditions, and never an easy thing to learn, but especially not if you are limited to 15s per flight and can only achieve a launch altitude that is typically lower than where thermals begin to rise. It happens, but Ive not often caught a thermal below 10 meter and it really only becomes 'easy' above 20 meter.
The unfortunate reality of DLGs is that to really have a good shot at experiencing what it is really like, you need to buy a pretty expensive composite DLG to achieve decent launch heights and have a realistic shot of catching a thermal. Or at least have up to 2 minute flights without thermals.