For the avoidance of doubt, I think the point you're making is that a public holiday that extends a weekend domestically in Thailand is not a public holiday in countries that come to Thailand on holiday that could cause a logjam of tourists at BKK immigration. Like Christmas. Or Easter. Or Chinese New Year. These international holidays could believably result in a logjam at BKK immigration if they could not be bothered to plan for them based on plane and passenger number arrivals - neither of which can conceivable be unexpected, unpredictable or unplanned metrics.