It's an interesting topic. Generally I prefer long sets, however in Circoloco I kinda like this approach. The djs need to bring their A game in a couple of hours with the pressure of knowing that they will be compared with the last ones, or the next ones... You don't have "warm-up" sets, you have raw talent/music from start to finish.
I've always get out of circoloco with the sense that dj A or dj B was the best of the night. (I'm a terrace lover, don't know if the same is true in the main-room, I never spent an entire night there).
The last circoloco I've been, I had Dj Tennis, followed by Tale of Us, then Troxler.
And for me Dj Tennis destroyed the place, it was awesome... and it was kind of interesting to see that Tale of Us, and Troxler couldn't build their sets with same consistency... Anyone of those guys would make an incredible all night set though! I think that is a great test for any dj, to play in that terrace.
One time, it was announced Martinez Brothers and then Jamie Jones (or the other way around), and they didn't do it like that... They didn't play 2 hours each, they've decided to do 4 hours of back-to-back instead...
Regarding the long sets, and to be fair, one of the most incredible sets I've ear there, was from Carl Cox during 5 or 6 hours (2013 or 2014). I don't think that happens alot nowadays.
For me Circoloco is still special and always a good surprise, unless is rammed! That is a no no... you can't even stand in your place for more than 5 minutes.
Again, this is just my opinion...