Some jurisdictions may unknowingly keep you in the dark about the timing of your application approval.
It is very possible that during the holidays, or any other time, one of the reviewers that must approve your project could leave for vacation right after your application gets to their desk. That could mean another two weeks delay, or more, on the time for approval.
Your project could also have just gotten approval from another department that was sitting on it because the reviewer was out sick for a week. When you call or go to the permit counter to check the status, find out what reviewer has it now, and where it has to go next.
Call the remaining reviewers on a weekly basis to find out what their expected completion date is for their review of your project.
Many times, you might be told not to call because they will let you know when it is ready. Do not be satisfied with this answer. Keep calling until you have an expected completion date.