ATTENTION MEMBERS:
People try to post; "how long do I have to be OUT of thailand when bouncing out/back or going to a thai consulate to buy a new tourist visa"?
The real answer is; there's no officially posted time you have to be out of thailand between entries.
What they look at when you come in on a visa exempt or tourist visa entry is your previous entry/stay history to thailand. <- That, more than anything else matters.
Also we've had people mistakenly think that buying a tourist visa gets you in to the country. Just because you have a valid visa for thailand in your passport doesn't mean you get in :O All it means is IF they let you in, you get in for the days allotted by that visa type.
We recommend anyone with an entry/stay history who is getting a tourist visa from a thai consulate to enter the country by land (if possible). There is far more scrutiny put on people with entry/stay histories comin' in by air than by land.
The other question people try to post is; "how many times by air can I enter on free stamp entries"?
Unfortunately the answer to that is "until they stop you from doing it" :O . Some people skate in time after time, some people get pulled aside on their second entry, there is abso-tively, posi-lutely no rhyme or reason to who gets in how many times without being questioned.
There is no official rule written that states people can have xxx visa exempt entries by air. It comes down to you can do it until you can't and believe me you'll know when you hit that 'limit' because they'll pull you aside, ask what you think you're doing and usually tell you next time you'll get denied entry.
Hope this was somewhat helpful (sorry it was long)
Safe travels everyone :)
TLDR : Answer Summary
There is no official requirement for how long one must stay out of Thailand when re-entering on a tourist visa or visa exemption; rather, the key factor is your previous entry and stay history. Individuals with a history of frequent entries may face extra scrutiny, particularly when entering by air versus land. While some travelers repeatedly use visa exemptions without issues, this is subject to change, and immigration officers have significant discretion. Generally, it's advisable for those with complex entry histories to consider entering Thailand by land rather than air to reduce the chances of denial.