In Thailand last year, we did a liveaboard to the Similan islands, and did 4 dives a day for 4 days. We got back, had 2 days off then 11 dives in 2 days at Phi Phi islands.
The dives generally all started at 30-35m, apart from the night dives, which were 15-20m. Nice gradual ascent up the reef, good long safety stops, etc. All dives were on air and only at the end of the 11th dive did I have more than 10mins of stops to do.
Some of these dives were over an hour long, but all surface intervals were a couple of hours at least.
In Egypt a couple of months ago however, the dive centre I was diving with have imposed a Max. of 3 dives a day. Again, most dives started on 30m with gradual ascents. Nitrox was used almost exclusively for most of our group and only once did I have any stops to do.
PADI do not have a maximum limit for number of dives (apart from in training) but there are special rules regarding minimum surface intervals when doing 3 or more dives a day. Also, if you are doing a lot of nitrox dives, then better watch you otu exposure, although, unless doing decompression, it is pretty hard to push the limits.
Latest thinking behind deepest dive first is that it might not be as neccesary as first thought, some people even advocate deepest dive last -
click here for some crazy divers speaking about deco .
For a bit of added safety, use nitrox, include a good safety stop after every dive and maybe extend your surface intervals.