Is it safe for US passport holders to enter Thailand repeatedly on tourist visas via Mae Sai?

any relation to the actor?

And in case you were wondering what those stamps look like, here are some examples

Okay, on Dec 31st 2016 they went back to 30 day visa exempt entries at land border crossings BUT at that time they also put a limit of TWO 30 day visa exempt entries by land in a year.

In Vientiane you're usually able to get 3 or 4 single entry tourist visas before they'll red stamp you.

As long as you don't have the red stamp you are safe going there because if they're going to put the warning stamp in your passport they give you one last tourist visa with the stamp on it.

I'd say IF all you're doing is waiting for a school to get you the paperwork so you can go to a thai consulate and get an ED visa just border-bounce at Mae Sai - Tachiliek and get a 30 day visa exempt entry. If for some reason the paperwork for the ED visa didn't come you could still extend that entry by 30 days at the immigration office for 1900 baht

It is safe till the consulate put a red stamp next to your visa. Than next time you have to switch consulates.

Mr. Blutarsky... zero... point... zero

Went lao vientian 4x in a row bro

You can go to Mae Sai, no problem. That's the easiest if you expect you'll have papers for an Ed visa within the next 60 days.