All depends on the insurance issued from your country some have limits of say 100 days. Some say longer but then you read fine print and a years insurance may only be valid for 60 day stints at a time.
Always a good idea to step back and look at situation before jumping in. Been here a long time seen many succesful buisnesses but seen hell of a lot of rip offs and scams also.
Dont do overstay especially in Samui, you get caught without visa you will be arrested, deported and probably banned from entering for maybe a year maybe 5 years