On Tuesday, September 5, 2017 at 11:06:47 AM UTC-4, Dan Marotta wrote:
I have alwaysÂ* wondered about the usefulness of having someone who's
never seen a particular make/model of glider "sign me off" as competent
to fly it.

Years ago I got a new-to-me glider model, and the insurance required a "cockpit checkout". I asked a CFIG for that, and after some futzing around the cockpit with me he wrote in my logbook that he checked the cockpit and found the glider airworthy. :-)