Personally, I hate being required to rush through scenarios and for that reason would not attend tournaments that are in the 3-per-day format. I want to enjoy my self while playing not to put time pressure on me - the standard workday has more than enough of that and I don't need that in my spare time.
Likewise, I don't see how the 2-per-day format could be bad for the hobby. As a newbie especially, I would not enjoy being steamrolled by that AFV-playstyle of: "Ok, start 1, 2, 3, 4, bp6, turn 7 bp9, sD - no, 9, up 14, stop & HD, 2 sides, CE fire, miss, Bow, CMG to turn 1MC. Done. Anything? Next." When "next" moves, he might still be wanting to consider if he had LOS on 4 and what his TH chances might be...
I believe there are simply different styles of play - the quick one and the deliberate one. Neither one is better or worse. They are simply different and ASL works for both styles of play very well. That said, the quickest and the slowest players might not go together very well, the former being bored, the letter being stressed.
In part, the 2-per-day format can cater to both if the scenario selection for each round includes smaller and somewhat larger scenarios. The slower players will tend to select the smaller ones as they realize they won't be able to finish the bigger ones. And if the TD has a rough idea which players prefer to go slow and fast, he can match the types together according to their current win/loss ratio. This won't work all the time, but it can go a long way.
von Marwitz