One of the many duties of an immigration officer is to assess the person in front of them and to decide I'd they are a genuine tourist or someone who is gaming the system and living or working in the country. This is true for any immigration officer throughout the world.
If you were presented with someone who has spent June, July and August in Thailand. Then has spent September, October and November in Thailand.
Information you have is that this person has a long term lease on a condo and has spent 6 of the last
***
months in Thailand.
Would you think the person in front of you was a genuine tourist?
My advice is get the appropriate visa for your stays in Thailand.