I have no idea of your experience, however I just did a CSU/Retract endorsement with about 70hrs. Did about 3hrs in a PA28R covering circuit bashing, and emergency gear extraction etc.
Not overly complex, however, it's (initially) a big workload step up compared to a fixed gear/fixed pitch; more things to think about and twiddle, and it's travelling somewhat faster while you do them.
I had intended to do it as part of a multi rating, but was convinced otherwise - good advice I felt in the event.