Generally a council works under the following guidelines for approvals:
10 days to respond to an application
3 sets of 20 days for information request
20 days for issuing an approval
All the days are calculated in working days. They would follow a similar system to assess op works.
Mos councils are under staffed and approvals are taking much longer than what they should. I you are not happy with then they you can take them court.
However, I take the approach of constant follow up...it helps if you deal with them often as they know who you are.