I have never changed a
tire. I could, probably, figure out how
and I expect I would muddle through if I had to, but I’ve never actually done
it. I keep that knowledge and experience
in someone else’s head.
For some people, trainers
are the someone else who keep the knowledge and experience for them. Clients show up and trainers direct them. It’s a workable system.
However, it is possible
to learn from trainers. A good trainer
should be able to tell clients what a particular exercise is good for, what
pitfalls to expect, and how to avoid them.
Sometimes trainers will tell you the muscles working, by name, and may
even go into exhaustive detail about insertion points, eccentric contractions, and
time-under-tension. Take what you want,
or let the trainer keep it for you.