Just make sure, when you come back, you have the Three Proofs (accommodation, onward ticket, and finances) to show if you get pulled aside and questioned.
Ah yes, that little-known but dedicated branch of the Royal Thai Police, committed to serving the whims of entitled farang members of Facebook groups who feel they've been treated unfairly, and to bringing to justice all those meanie Facebook group admins who delete off-topic comments.
The days of being able to live here indefinitely on back to back tourist visas, and border bounces are very much over.
The more such visas & stamps you have, the more likely it is that you'll be questioned or even denied entry, though a lot depends on the views/attitudes of the individual officer you're in front of.
It all depends on the individual immigration officer in front of you.
I've come across accounts of people being asked for the three proofs at every crossing I can think of - even when they already have a visa approved.
Its even happened to friends of mine who came here with *no* previous history of staying in Thailand in their passport.
It costs $10-20 to "rent" an onward ticket (cancelled after a few hours), and its easy to make a no-prepayment reservation on Booking dot com & cancel it later.
Better safe than sorry, and have the three proofs with you.
Got pulled aside at Chiang Mai airport and questioned coming back from Kuala Lumpur, and asked to show the same three proofs I'd already had to submit in Kuala Lumpur to get the tourist visa in the first place.
I'd had two border bounces, the second of which I'd only done a week or so before, so as not to have to go on a visa run on my birthday.
They were making an issue of the fact that I'd been in Thailand for years - even though, for all those years, I was legally working on a Non-B visa, and had quit my job just over two months before.
Onward ticket or return ticket amounts to the same thing.
Its now official policy that you have to show a ticket both in and out of the country, though some consulates might be following that guideline less strictly than others.
In Vientiane, for example, they're less stringent about the ticket *into* Thailand, understanding that most tourists will be getting a taxi to the border and then hopping onto a bus or minivan.
However, even at Vientiane, people have been getting turned away for not having a ticket *out* of Thailand (call that ticket whatever you want, it amounts to the same thing).