When a cell is congested due to lack of resources, ie SDCCH TS, it will keep on retrying until it succeeds or exceed max retry. This increases the attempts.
First, increase the #SDCCH and see if it helps. If fails,
Make sure that this cell is not at a BSC border, or a LA border, or at a place with high LU such as highways. You may want to check your Periodic Update timer to ensure that it’s not too short, ideally at set at 4 hours.