At my club, experienced pilots get an annual session of refresher training which includes launch failures. This seems entirely sensible to me, as modern winches rarely offer up a real failure and aerotow ropes hardly ever fail (if inspected regularly). New pilots begin with a regular check regime, and out of check pilots probably get a launch failure practice on their check flights.
Of course, if you are witnessed using poor launch technique then you will probably be invited to demonstrate the correct way to an instructor, as he or she has to write the accident reports if you can't cope with a real emergency.
I've witnessed a few real launch failures where the pilot didn't cope properly, and in all cases they were pilots about whom the instructors had concerns - pilots with poor decision-making, or over-confident pilots (often very experienced) pushing the envelope. Funnily enough, it tends to be these types of pilot who object to regular launch failure practice.
Annual practice seems to be enough for the rest of us to fly safely.