This one I just used and it was an accident.
Wife wants to go see Duran Duran. Found the seats we wanted, 5 and 6. (They're starting to charge a $20 premium for the first two on the Aisle). I got to the cart and realized I only clicked on seat 5, not 5 and 6. They hold it for 7 minutes to complete the transaction. So I went back and looked again for tickets, seat 5 unavailable because they are holding it from my previous selection, so I took 6 and 7 and bought those. If you were to try initially to buy 6 and 7 they wouldn't let you leave a single seat in between when 3 and 4 are occupied.