Howdy!
Oh my... what I did on my latest dive trip (a live-aboard over Memorial Day Weekend) where there was no designated DM, I used my judgement about diving. I tended to dive every other dive site, since my surface interval hadn't been long enough between some of the boat captain's dive sites.
I did NOT check the PADI tables that I brought, as I relied on a SI of more than 1 hour (in most cases it was more than 2 hours, but on one case was about 40 minutes).
I did my deeper dives first. And watched my computer to avoid Deco Divin'. But generally did not come near those limits. Since all of the dives were about the same length give or take one or two minutes, I make a longer SI after deeper dives.
So I watch the computer to see the length of my SI, trust the computer while diving, and have gotten out of the habit of checking tables and planning repeat dives (other than knowing to dive shallower during each successive dive and confirm with my buddy that plan). We also did a safety stop every dive. And that was our plan, not mandated by the boat crew or any DM.
So it's not a matter of trusting a DM (even if one WERE present on my recent dives), but trusting my computer instead of planning and using tables. (Which would otherwise be too conservative, and sometimes tell me I shouldn't even get wet.)
I would NEVER dive, following blindly along a DM (or anyone else) without using my own computer. If I did not have a computer, then sure as hell I would use Tables. I always dive for MYSELF, using my previous dive data, current state of being (cold, strenuous, tired, etc), current computer readout, and would only follow a DM as a guide to the local life. If it's time for ME to surface, I signal the DM that I (and my buddy) am heading back.
Hmm... what was your question?
Have a better one
. paul
http://www.myscuba.com/getdeep/