(20 Dec 2015, 1:24 pm)Kuyoyo wrote Everything at Stockton - bar the 5, 7A and 15 - interwork in some way on Sundays (Buses do 9s break then the 17/27/27a/28b/X12 cycle, or do 27a/27 break and so on). To take the X12s out, you'd then end up with buses having long layovers between trips as there used to be when the 9 and 27/27a ran on their own. The 17 can't be done in an hour while running to Ingleby. 28Bs can't fit into an hour and it's not worth running it half hourly. The way it works is the most effective way.
As had already been stated above your post.