Allow bookings for multiple people to take up adjacent timeslots

The multiple quantity addon is great for things like classes where someone may want to book for multiple people at the same time, however many services are really meant for one person per appointment and it would be great to allow the booking of multiple quantity to increase the required appointment duration by multiplying the appointment duration by the quantity number during the timeslot selection.

Example:
Man wants to get a 30 minute haircut for him and his brother, he selects 2 of the same haircut and then is required to choose a timeslot for 1 hour.

The cart addon aids in solving this sort of scenario already but it is further complicated by the fact that you must select 1 timeslot of each of the items in the cart. Most of the time people wish to have adjacent timeslots from our experience. So another option may be to fix the cart addon issue regarding timeslots.