well it is 60 days on the initial Tourist Visa (TR) followed by a 30 days extension, followed by one visa run and one more extension to get to the 5 months.
Thai embassies are issuing 60 days (ok not 90 days) Tourist visas. You can apply for a the 60 days Tourist visa (TR) at a Thai Embassy outside Thailand. They come single entry and multiple Entry. Towards the end you can apply one time for a 30 days extension, tust giv4s you a 90 days stay in Thailand. You then need to exit (ideally by plane) for a couple of days and when you come back you get a 30 days visa which again can get extended by 30 days, makes it 5 months if you add the days you stayed outside for the visa run. Let me know where I'm wrong here.
What is the length of the Tourist visa one can apply at the Thai Embassy in your country? I understand there is a multi months Tourist visa when you apply for it at the embassy.
You can apply for a three month Tourist visa at the Thai embassy in Prague, fly in and stay for three month and then extend for another month. After that four months in Thailand you have to make a visa run into a neighbouring country by plane and when you arrive in Thailand again you will get a 30 days visa which you can extend at the end for another 30 days. 6 months with one travel to a neighbouring country.