What is the time frame for repeating the visa exempt entry to Thailand after leaving?

The question revolves around the time frame for repeating a visa exempt entry to Thailand after a short stay, specifically after a 30-day visit followed by a month in Vietnam. The consensus from comments indicates that there is no specific time frame—it is essentially a case of re-entering under visa exemption each time. However, it’s suggested that if someone frequently uses this option, it may raise concerns over visa legitimacy. For those worried about such issues, obtaining a tourist visa for the initial stay might be a safer option.