I’m not arguing with people who say you don’t need a year but my personal experience is that when I entered 10 days ago they pulled me to one side and checked I had a year Thai heath insurance at immigration at the airport.
May be they didn’t know.
From comments I have previously read it seems you don’t need a year.
It may be best to look at the Thai Embassy site to get full explanation.My take it’s for over 50 year old you apply in your own country and you have to show financial details have health insurance in Thailand and have a medical certificate completed and last 1 year initially.