Technically, there’s no limit by air. But you’re eventually going to be pulled aside by the immigration officer and questioned why you’re spending so much time here via the exemption stamps. You can keep rolling the dice. You’ll soon roll snake eyes and end up denied entry. I would suggest you start entering with the proper visa. A lot less hassle and a better chance of not being stopped. I would also suggest you have everything in order when you arrive. Proof of accommodation, 20k baht (or equivalent currency) cash and an onward ticket out of Thailand within 30 days.
As you can see, I circled the OR as in you need one of the two. But from what I know, you can do the 65k baht per month after your initial year. The pros will chime in soon enough.