Sorry to bump up this old thread, but I wanted to clarify something. I probably didn't express it well. In those warm waters, our DM did something that is probably described as just "making good use of time/depth." Not really pushing it.
I was diving my husband's Tusa IQ-800; it has conservative setting options, and he had set it so it was actually one click more conservative than the "standard" setting. (Being new fat divers we figured that might be a good idea.

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My DM's watch beeped when the NDL limit approached, and I could hear it. The area we were in was very sloping, with lots to see. I noticed his computer was set a smidge more conservatively than mine. We headed to our deepest point, and we stayed there until his watch beeped, and we rose up slightly, perhaps only 5-8 feet. Of course, that gets you minutes. It would beep again, and we'd rise again. We remained on that edge and used it to guide our ascent because what was down was cooler than what was at 30 ft or so.
After doing that for two very long dives, I felt pretty strongly that I was pushing my nitrogen loading more than usual and wanted to make sure we waited to fly.
(I was thrilled to be the LAST one on the boat both times, getting an extra spin around the block with the DM because my gas usage was awesome.)