It's odd that a NAUI instructor hasn't jumped in here.
My guess is that you need to meet the course requirements here:
NAUI Worldwide Master Scuba Diver So, you need AOW and you make 8 dives during the MSD program. Since you can only make 3 per day, it takes at least 3 days.
I would also guess that NAUI Rescue is going to be
similar to PADI in that there will be a long day in the pool followed by a series of scenarios in open water (PADI is 4 dives). There is also a classroom session.
Back in '88, the sequence was OW I (5 dives), OW II (6 dives), Advanced OW (8 dives) and Rescue (1 skin dive and 2 LONG OW sessions). In later years, this sequence could be traded in for the current MSD although back then, there were even more dives required for MSD which is now Gold MSD and no longer offered AKAICT.
So, I would expect the number of dives to come out about the same and it's true because the current MSD program is 8 dives which accounts for the old Advanced OW.
Rescue is required for PADI MSD but it's not clear to me that it is required for NAUI. But NAUI doesn't require specialties to get to MSD because they make up for it in the MSD course. PADI requires 5 specialties (some of which don't require getting your hair wet) but they don't have an actual MSD course.
I don't recall the details of the NAUI Rescue course but I do remember that we had to be First Aid and CPR certified. That is the same for PADI. PADI offers a course for First Aid and CPR but you can get it anywhere you wish.
For NAUI, MSD is a certification. For PADI it is only recognition that you have taken 5 specialties. Huge difference! In the NAUI program, you have to swim for your card.
Richard