According to this notice, that was in Suratthani Imm office today, you can do 4 months worth of visa exempt entries before needing to get a visa !

Not sure how they came up with that.

It would depend upon whether you did it by land or air. At some border crossing you can get one after flying in.

By air perhaps one or two if you stay for the entire 30 days and then just go out and back on the same day.

But there is no need to do one after your first entry because it can be extended for 30 days at immigration.

Interesting.

But 4 months does not mean 4 entries. As each entry can be extended by 30 days it can mean only two entries and extensions.

Just reporting what I saw...

Doesn't bother me as I'm on a Non O but thought others might be interested.