just to get the terminology correct, you are planning a border run unless you plan to get an actual visa in the other country.
If this is your first border run, you should be able to do an extension for 30 days and then do a border run for 60 day visa exempt entry. ; however, after that any subsequent border runs become more likely to raise a red flag to the immigration officer. Nothing is set in stone, but that is my experience.
yes. If a person maxes out the 60 days and then extends for 30 days everytime, it is a red flag to immigration. Of course, I think two visa exempt and two extensions for a total of 180 days is just as bad as three visa exempt for the same 180 days.
it is up to the immigration officer, good that you didn't get extensions but you might get flagged. If you want to continue staying several months per year, I suggest you get a longterm visa. Chok dee