It's about The FAA EXEMPTION. The FAA grants glider pilots an EXEMPTION from the requirement of having an A&P make a logbook entry each time we assemble any glider because all glider pilots have received training in assembly.. If a pilot has not logged the training from a CFIG then you technically cannot put the wings onto a glider. The SSA staff worked with the FAA to obtain this exemption many years ago. Find it on the SSA website.
As a Designated Pilot Examiner, I look for this training along with ALL of the 19 pre-solo FAR 61.87 mandatory training items along with the type of launch endorsement, typically aerotow. Further, I've learned that some CFIG's have failed to provide a Pre-Solo Written Test for each model of glider a student will solo and make an entry into the student pilot's logbook. One pre-solo test is not enough if the student starts in a Schweizer 2-33 and later solos a 1-26. Same for PW-6 into PW-5, two seat or into any single seat glider. Each requires a pre-solo written test generated by the CFIG for each glider. Note that all pilot examiners are required by the FAA to look very closely at the applicant's logbook (as well as the glider logbook.) To avoid the embarrassment of rejection just before the checkride begins, I ask the applicants scan their pilot logbook for these mandatory endorsements from their CFIG in advance and e-mail these to me. If an endorsement is missing, we cannot begin the checkride. Blame it on the CFIG?