I use SAC, but in kind of an indirect way.
When looking at dives (either square profile or multilevel) to see if the plan is reasonable for the amount of air, I total up the ata-minutes. By ata-minutes I mean time at each depth in minutes, multiplied by the ata for that depth.
For an AL80, I need to have ata-minutes less than 130, or 160 at the very most, and that only for multilevel dives where my rock-bottom reserve gas for ascent is very low for the shallower portions of the multilevel. (130 ata-minutes is the result of assuming I have 65 cubic feet available, and SAC of 0.5).
I most cases, I have already done the profile being considered, or one very similar, so I don't have to actually do the calculations.
If I am planning a dive with an instabuddy that I've never dove with before, I assume 80 ata-minutes available, or 100 ata-minutes at the most. Those numbers correspond to 65 cu feet with 0.8 cfm and 0.65 cfm SACs.
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Turn pressures, ascent pressures, and rock bottom take priority over any previous planning.