I confess I no longer drink a series of discrete shells.
In a typical sesh I will prep a bunch of grog. I then might or might not do a small series of 4 oz shots just to get me fairly quickly where I want to to be, usually one or two, depending on the grog. And then maybe 20 minutes later one or two more, again depending. Or I might immediately go to stage 2: the big tumbler full of ice and grog and I just sip or glug from that, and refill, depending on my whims. Supplemented at some point usually by a KWK concentrate cocktail and various candies. I tend to hit a particular point and just stay there, usually for 3 hours or so,maybe 4, and then start winding down, drink water, do some work or go to bed.
So, I guess the question doesn't apply to me or the way I drink grog.