My personsl experience.
OK just flew in on 60 day visa exemption.
The landing card completed fine.
I was questions by the IO on how long I was staying.
They asked where I was going and I presented an invitation letter from my fiance detailing where i would stay and scans of her address book and her identity card. They gave a little nod and finally checked where I was staying that night before my flight to phangan in the morning. Then stamped it.
Overall about 3 minutes, but I believe facilitated by clear paperwork.
The adage better to have it and not need it than need it and not have it.
Fir reference I spent 39 days in September to October 2024. And 30 days February to March 2025 before this trip on may 15th.
I have a 52 day trip planned for September but I am going to apply for a proper tourist visa as it may save hassle with visa exemptions