I have heard that there is a limit to two border runs per calendar year when using Tourist visas and/or stamps on arrival, but I cannot get it officially confirmed anywhere. Does anybody know what is true for this?
TLDR : Answer Summary
Yes, there is a limit to two border runs per calendar year for those entering Thailand using Visa Exempt Entry at land or sea borders, though this does not apply to tourist visas or arrivals by air. Thai Immigration Officers have the discretion to approve or deny entry, especially if there is a history of frequent visits.