I must admit I'm still quite surprised at how well some of the non City Centre routes do when it comes to passenger numbers. I hadn't used the 8 in a while but it was very busy today and when I see them after work they're normally packed.
I think it creates a headache though when it comes to adjusting services based on how many drivers First are short of because you realistically can't cut the orbital routes more especially the likes of the 8, 46 and 90 because capacity wise they'd struggle hourly.
One I never thought I'd think would be possible was the 6 going to every 20 mins but from what I've seen of it recently you maybe could get away with it. The 2 being every 15 mins if it got more double deckers is another.