Augustus:what i mean is i would rather hang out on the water for the day , getting a nice surface interval relaxing and then do the second dive then rushing out to a site on a fast boat so I am back at the dock for lunch. I avoid fast boats for this reason.
Not all fast boats rush you back either...although of course there are some that only give a 20 to 30 minute SI so they can hurry back. We do a minimum of 1 1/2 hour SI on shore somewhere and don't dictate bottom times. We schedule our afternoon dives a bit later than other shops as well so we don't have to rush the morning divers. They can do long dives with a long SI and be back by 1:30ish without being rushed at all.
The points many on this thread are bringing up are more operator dependent vs. big boat vs. small boat dependent.