Should I book a flight in advance for my next exit when returning to Thailand?

The user inquires whether it's necessary to book an exit flight for their next departure from Thailand, given that some travelers were reportedly required to do so. Additionally, they ask for advice on which entry point—Chiang Mai or Bangkok—is more efficient. Comments suggest that Suvarnabhumi Airport in Bangkok is easier than Don Muang but do not confirm the need for an exit flight.