I dislike it personally, and I consider it a fast-food approach to tango; but I defer to the organisers whenever they wish for me to play three-song tandas.
Oh, I definitely prefer four-piece tandas! I'd prefer that milonga and vals tandas have four pieces, too . . . I've never really understood why they're three pieces. However, some orquestas – or some works by some orquestas – really, truly don't stand up to that.
I prefer the idea of having one/two rotating tandas, where partners are switched every song, and the aim is to dance with someone you've never danced with before.
I'd love it if more organizers had the guts to play partner-switching games.
I think that
within a tanda, it's rough! I just had a conversation with a follower, in which I explained that I need more than one tango to adapt between partners. For me, the first tango in a tanda is all too often close to disposable for that reason.
However, rather than two- and three-piece tandas, I'd love to see things like "Leaders put your names in the hat. Now followers draw names," "Followers put your names in the hat. Now leaders draw names," and even blindfold invitations with a reveal at the end. Not all evening, and maybe not for more than one or two tandas, but once in a while. Use Halloween, the International Day of Tango, or Gardel's birthday as an excuse if you must. Bring
fun back to tango, which is often far too serious and formal for its own good.
You have a point about overstaying their welcome, though; I find myself thoroughly bored by the third song of a less-than-perfect Tanturi tanda (if I bother to dance it), Troilo/Marino, or a badly composed Pugliese/Chanel, Rodriguez/Moreno or D'Agostino/Vargas tanda for example. Some late Pugliese, too.
My issue with a lot of the later, "radio tango" music isn't that it's
bad – on the contrary, I adore it and love the challenge of dancing it. It's that the pieces are long and, being composed as much as or more for listening as for dancing, often difficult to interpret well for any length of time. Sticking to length, I think that if your three-piece tanda is as long as any four-piece one from the Golden Age, it's best to stop at three. By the same logic, though, if a three-piece milonga or vals tanda blows through in the time it would take to dance two tangos, maybe consider adding a fourth piece.