Unless there are rule changes I have not seen, there is no minimum time for differences, in fact my understanding is an instructor
can even sign differences off with a briefing - I think the only one this might be half sensible for is retracts, even then best to do a few circuits. With the right ability it
is possible to cover tailwheel conversion in an hour or less but 5 hours is realistic for most people, especially if you cover
all the bits that should be in this:- three pointers, wheelers, crosswind.
