Backpacker, could you explain what a safety altitude at 50 meters involves? safe for what? the 150 meter abbreviated circuit call, would that be 450 feet? not a lot. If this is a mantra recited before every launch, it will not require any thought or planning. I feel that rigid drill of this sort does not take into consideration the variety of airfields we use. At Lasham, for instance, any cable break is a land ahead, because the field is so big....and it really should be the FIRST CHOICE! If you are programmed to do an abbreviated circuit from 450 feet, is this best practice?
Seems to me that each gliding site will have particular assets and limitations, and the student should explain carefully, before flight, his plan in the event of a launch failure. On a strong headwind day, you can land ahead from almost any height. On a very light wind day, or cross wind, or whatever, the student must be able to adapt and plan for conditions.
Back in the days we winched with piano wire, we were pleased to get a launch to the top without failure, it was a common event. I pulled too hard one time, broke the wire at about 700 feet, which came down like spaghetti all over the winch, and decided to spend the next couple of hours soaring.....anything but return to face the music!