I really don't think Punki's scenario fits the "back-to-back" moniker. A classic back to back is indeed somewhat "tricky" because it involves OVERLAPPING tickets

e.g.
Ticket 1:
OCT16: IAD-SFO
OCT28: SFO-IAD

Ticket 2:
OCT17 SFO-IAD
OCT27 IAD-SFO

Actual itinerary:
OCT16: IAD-SFO (from ticket 1)
OCT17: SFO-IAD (from ticket 2)
OCT27: IAD-SFO (from ticket 2)
OCT28: SFO-IAD (from ticket 1)

Two San Francisco trips at discounted fares with overlapping tickets. Clearly a violation.

But what Punki supposes is that you take your home and desitination and reverse them. So all you are really doing is buying a series of consecutive discounted tickets. There is no overlapping tix and no violation, as Punki's dancer analogy makes clear...who the heck is the airline to say where your "regular point of embarkation" should be?

But what I really like about Punki's idea is that it means you are always "on the road" when you are sleeping in your own bed since you are in the middle of a ticket and you are "home" when on travel since you are in between tickets..which is how many of us have felt at one time or another anyway...

BTW, I mentioned this to a friend over the long weekend who commutes each week to Boston (up on monday, back on friday) and suggested he try this. Turns out he figured it out months ago and has been doing it since, the BOS-IAD weekend fares being about half the price of the IAD-BOS midweek roundtrip fare...