Can my friend extend their tourist visa at Mai Sai and how does the 30 days land crossing rule work?

A user inquired about extending a tourist visa at the Mai Sai border, specifically regarding the current rules on land crossings and whether they can still receive 30 days twice a year. Comments clarified that as of December 31, 2016, travelers can only obtain a 30-day visa-exempt entry by land crossing, with a limit of two such entries per year. Further discussion touched on whether the friend had already extended their visa at an immigration office.