Kinda depends for me...either way, I break with what I am playing with. Switched to a harder, single layered tip, so no worries there...LoL!
Generally, when I am playing a league match, I will carry my 2x4/3x4, simply because, well, just never know. Also, since no one ever has a maintenance tool of their own, I usually maintain the team's cues, with regards to their immediate needs.
For just 'shits-n-giggles' play or even tournaments, I am perfectly happy to carry one cue and and my 1x2 case. Since MY needs are pretty simple while playing, I have a Crown Royal bag that carries some extra chalk and quarters and a tip shaper that I can throw into my purse.
Considering that the bulk of the players on the planet are still the 'newbie' players, that and league...I would venture a guess that actually the 1x1 is the most sold case config, closely followed by the 2x2. Think about it...they wouldn't still be making these if these were not popular.
As to many of those folks here at AZ...especially those who have been here a while...I am bettin' that the 1x2 is still extremely popular...lotsa folks who collect higher end cues have a special case for each cue. I would say that that is closely followed by the 2x4 config...partially because of the advent of the j/b cues' popularity, or...some just like to carry a 2nd cue, because, you just never know.
From the 2x4, I am gonna guess the next most popular config is the 4x8...followed closely by the 3x6. This is the point where the cue addiction has set in, but is still fairly fresh...compelling one to carry all their nice cues together, partly to play with...some to showoff...LoL! Gotta tell ya...I cannot see me ever getting to this point, simply because I am just not all about the weight of the loaded cases at this point...not to mention, there is simply too much on the line in the advent of a theft. This would suck in a big, big way.
I will tell you this...I look more at the player who arrives with a 1x2 case. It takes a certain amount of confidence to show up with just one cue to carry you throughout a match or tournament. Not only confidence in one's playing ability, but confidence in one's cue, as well.
Lisa