Might? I have extended over 30 tr visa and visa exemptions in the last 10 years. Nit picking. The question was how long can they stay without a visa, and the correct answer is 60 days, like I said.
Please know what you are talking about if your gonna try and help. The correct answer is 60 days. 30 days when you arrive and you can extend 30 days in Thailand.
Other people can help you more with this question, but I will throw some advise your way. Many jobs, especially English teachers will ask you to work while waiting for the visa paperwork. This is illegal and if caught, you have to deal with Thai courts and yes, jail until you get bail.
There is no limit on tourist visas or air entries, nor any limit of any kind on time in Thailand. That said, you can expect hassles and questioning eventually from immigration.