Why is my 1 year visa application taking longer than the usual 30-day consideration period?

The user has applied for a 1-year visa based on marriage to a Thai citizen at the Chiang Mai immigration office and is waiting for a longer-than-expected processing time. They received a stamp indicating a return date nearly two and a half months after the application, causing concern since they have heard the normal consideration period is around 30 days. A commenter clarified that the 30-day under consideration stamp is typically added to the expiration date of the applicant's current visa.