It will be interesting to see the results of the survey. It seems to me the charging capacity is limited by the kW made available to the chargers. If there is 66kW spread across 12 L2, or 2 L3, that is the same daily charging capacity. My guess is installing and maintaining 12 L2 is less expensive than 2 L3, but that is just a guess.
So I don't think L2 or L3 allows more cars to be charged - it is all about the kW made available. 8 hours should be plenty of time to charge on L2.
It isn't that you can't do it with L2. The problem is that it requires a complex scheduling algorithm to achieve a comparable level of efficiency. Let's say you have two spaces and four cars that need to charge. Two cars need four hours of charging, one needs two hours, and one needs six hours.
8:30 Car A arrives and needs four hours. Stall 1 is occupied until 12:30..
8:40 Car B arrives and needs four hours. Stall 2 is occupied until 12:40.
9:30 Car C arrives and needs two hours.
9:45 Car D arrives and needs six hours.
12:30 Car C is allowed to charge. Stall 1 is occupied until 2:30.
12:40 Car D is allowed to charge. Car D needs six hours, but can only stay for 5:05. Car D has to go to a supercharger anyway, and thus doesn't bother to charge because it wont' save any time. Stall 2 goes unused for the rest of the day.
If you could somehow know in advance of the existence of cars C and D, you could do it like this:
8:30 Car A arrives and needs four hours. Stall 1 is occupied until 12:30;
8:40 Car B arrives and is asked to wait until 12:30.
9:30 Car C arrives. Stall 2 is occupied until 11:30.
9:45 Car D arrives and needs six hours.
11:30 Car D is allowed to charge. Stall 2 is occupied until 5:30 (before the 5:45 departure).
12:30 Car B is allowed to charge. Stall 1 is occupied until 4:30 (before the 4:40 departure).
But doing so requires perfect future knowledge of what vehicles will arrive when, and how much charging they will need. This is, unfortunately, unachievable. Even getting close is tremendously difficult.
Compounding this problem is the fear that you'll end up preventing someone from getting home by taking an L2 charging spot for 6 hours, whereas the risk of doing so goes away with L3 charging, because any car that supports L3 charging could also use other L3 charging nearby if the workplace charging never becomes free. So users are more willing to charge beefier cars like the Tesla if L3 charging is available than if only L2 charging is available (unless L2 charging is so abundant that there's nearly one charger per car, but this is rarely the case).
And further complicating things is the fact that supercharging tapers its charge speed based on SoC. So charging a near-empty Tesla at L2 speeds for three hours only saves you five or ten minutes at the supercharger later. At that point, it isn't even worth walking downstairs to move your car. So that results in even less utilization at the end of the day than you might otherwise have.
If you switch to an L3 charger, the relative speed makes scheduling much easier. The shorter the charging period, the easier it is to schedule fairly, because a user is much more likely to be able to stay for an extra few minutes than an extra few hours, which means the latter part of the day becomes much more fully schedulable.
Obviously an L3 charger takes the place of O(6) stalls, rather than just two, so I won't even try to shoehorn the example above into that arrangement, but mathematically speaking, L3 charging is superior to L2 charging for all the same reasons that having a fast single-core CPU is superior to having a two-core CPU where each core is half as fast.