@Hector *******
, The principle of a multiple-entry visa is that you can enter Thailand as many times as you want during the visa validity, not maximize your stay.
But it's true less hustle to travel around and enter Thailand with a valid visa than repeating entry on visa-exempt, especially with airlines.
Speaking of maximizing your stay, you may be able to stay in Thailand for almost 270 days max with the latest entry and the last tourism extension.