How long do I need to stay in Malaysia before returning to Thailand with a 30-day visa exemption?

A French passport holder with a current tourist visa in Thailand is asking how long they need to stay in Malaysia before returning to Thailand to qualify for a 30-day visa exemption. Responses indicate that while technically there is no strict time limit, a stay of three days is generally acceptable. However, regular short trips may raise questions with immigration authorities, so it is advisable to avoid making this a regular occurrence.