Master Shot First?
 

For the sake of discussion, let's say your longish scene is a couple having an argument while Her Friend looks on. Do you shoot the Master shot first as a benchmark for everything else, then get Him, then Her, then Her Friend's reaction shots, or do you start the other way around with the hope that by the time you've finished Him, Her and Reaction, everybody will have settled in with their performances and the Master can be done in fewer takes?

I almost always do the master first and then the cut-aways. But then I'm working under very limited time with students and have maybe 45 minutes to capture an entire scene. Since we will shoot 2 scenes in 2 hours, twice a week for 5-6 weeks, we find that running through the entire scene gives everyone a perspective and we can handle acting issues up front. Seems to make everything go smoother and quicker.

The only time we do a cut-away first is if that just makes everything easier or there is some external reason to do so.

You MUST do the master shot first, in most cases. If you did your reaction shots first then everyone would have to, simultaneously, match the master shot later.