Real-life example: You are running ads on your busses. A bus might already be booked by another client or might be out of order as it has to run through service. Line A has 7 busses. What options do you have to set this up in the booking calendar to show your staff what is currently still available?
The booking calendar will show each product with a 7x (as you have 7 Busses) if you do not show the individual content as a column.
If you show the content column each bus will show up with the availability of 1x.
Having set the constant quantity to one will make sure that the system subtracts only one of the total if a bus has been booked/blocked.