Further to the original post. There are occasions like the one described (50 hours and no solo) when the CFI must take responsibility for this type of student. Much of the time where students are taking an inordinate time to solo ie 15 hours or more, the CFI should be aware of this and in any case should be checking a grade 3 instructor's students by flying with these students to check on quality assurance. Too many times do we see CFI's allowing their instructors to fly on and on with a student when it is obvious from the students progress reports (if the CFI ever takes the time to study them) that either a change of instructor is needed or the CFI should fly with any difficult student himself. CFI responsibility to keep a very close eye on new instructors is often abrogated to a grade 1 or 2.
The 50 hour problem student should have been picked up at the 10 hour mark at least and the CFI directly involved. Often the CFI prefers to be training IFR students himself and lets his grade 3 and 2 have unfettered reign at GFPT students. This is unfair to students who have the right to request a grade one instructor for ab initio flying.