Something to seriously consider if you plan on staying permanently in Thailand, on a type O visa extension based on marriage you can work. On the type O visa extension based on retirement you can not work. This is a serious consideration because by working in Thailand, and making at least bt40,000 a month, married to a Thai, and paying income tax for at least three years, you meet the main requirement to apply for permanent residency, or apply directly for citizenship. You can't do this on any retirement visa type. There are other requirements, but they mean nothing if you don't work. This is something to seriously consider. With permanent residency you are done dealing with immigration, then with citizenship you can own land, plus other benefits.
Understand that immigration stereotypes and profiles. They modify these all the time, as new repeated abuse, and questionable loopholes are discovered being used.
the seven days is misleading. If you were to go to immigration trying to get a second extension, they will refuse you, and maybe let you get a 7 days to leave Thailand stamp, but it is not automatic. They can, and do refuse it.