Assuming that the constraint is charging power and/or supercharging hardware - the superchargers should be installed with more plugs( and parking spaces ) than charging units.
Software should maintain a queue and a switching system should route charging power to the plug that is next in line.
For example: if you have 4 90kW superchargers available you could put in 8 plugs.
8 cars are parked, all 8 are plugged in. 4 are charging with 90kW available to each. 4 are waiting. When one car finishes, its owner is notified and the other car starts charging.
No time is lost moving vehicles in and out of spots. No time is lost waiting for the owner of the car that finished charging to come and disconnect and move.
A 9th vehicle needs to be moved into position when notified that another car has vacated the charger, but will still be waiting in queue.
Ideally charging is divisible in increments, perhaps of 10kW and the supercharger power is routable to all plugs, just as long as it doesnt exceed 360kW.
So all 8 cars could be charging, some at the full 90kW, and some at some partial power.
If this is not technically possible, then perhaps a hybrid system where the 4 superchargers route their power to the 4 frontmost cars that need more than 10 or 20kW - and the other cars receive 10 or 20 kW of AC power.
So if you have 8 cars in queue and they all need a full charge, the first 4 cars would get to near full and then drop off supercharging when the charging current drops under 20kW, they would switch to AC charging ( receiving <= 20 kW ) and the next cars would receive supercharging.
If the total power limit is 360kW, the front 4 cars may be receiving 20kW each, and the next 3 cars would be receiving 90kW and the 8th car still waiting.
With this system it would be reasonable to have more than 2x as many plugs as superchargers.
The ratio of plugs to superchargers really depends on how much time is wasted waiting:
1 - for someone who is done to come and unplug their car
and 2 - for the tail end of the charging top up when power drops down to low levels ( 20kW or so )
Software should maintain a queue and a switching system should route charging power to the plug that is next in line.
For example: if you have 4 90kW superchargers available you could put in 8 plugs.
8 cars are parked, all 8 are plugged in. 4 are charging with 90kW available to each. 4 are waiting. When one car finishes, its owner is notified and the other car starts charging.
No time is lost moving vehicles in and out of spots. No time is lost waiting for the owner of the car that finished charging to come and disconnect and move.
A 9th vehicle needs to be moved into position when notified that another car has vacated the charger, but will still be waiting in queue.
Ideally charging is divisible in increments, perhaps of 10kW and the supercharger power is routable to all plugs, just as long as it doesnt exceed 360kW.
So all 8 cars could be charging, some at the full 90kW, and some at some partial power.
If this is not technically possible, then perhaps a hybrid system where the 4 superchargers route their power to the 4 frontmost cars that need more than 10 or 20kW - and the other cars receive 10 or 20 kW of AC power.
So if you have 8 cars in queue and they all need a full charge, the first 4 cars would get to near full and then drop off supercharging when the charging current drops under 20kW, they would switch to AC charging ( receiving <= 20 kW ) and the next cars would receive supercharging.
If the total power limit is 360kW, the front 4 cars may be receiving 20kW each, and the next 3 cars would be receiving 90kW and the 8th car still waiting.
With this system it would be reasonable to have more than 2x as many plugs as superchargers.
The ratio of plugs to superchargers really depends on how much time is wasted waiting:
1 - for someone who is done to come and unplug their car
and 2 - for the tail end of the charging top up when power drops down to low levels ( 20kW or so )