The flying club I am a member of has 700+ members and 15 aircraft (+/-).
I have been a member of this same club for 25 years. In those 25 years,
I have had only two flights that I have cancelled and grounded the
aircraft.
One was a C182Q with high oil pressure. I knew something was wrong as I
flew this aircraft often and knew what was normal. The troubleshooting
in the shop found a cracked case.
The second aircraft I grounded was a PA28T-201RT (Turbo Arrow IV) which
backfired so badly during runup on the right mag I thought the engine
was going to come apart. The right mag was shot.
Other than those two instances, I have flown aircraft with intermittent
comm radios and panel lights that would not illuminate the gauge they
were attached to. Each of these was overcome with backup solutions
(second comm, EL rope).
The aircraft in my flying club are flown often by pilots with a full
range of experience. Between the instructors flying with the students
and the high time pilots mingling with the low time inexperienced
pilots, any mx squawks get picked up quickly.
The club is usually quick to take care of serious deficencies, although
the inoperative fuel gauge on one aircraft was deferred until the next
scheduled trip to the shop. This did cause me an actual pucker because I
lost track of time flown on that tank instead of watching the fuel
totalizer.