Noticed a few things today that make me question the sanity of Nexus

Birtley Station Lane stop

21 to Newcastle - Journey time 28 minutes
X2 to Newcastle - Journey time 32 minutes!!!

yet a few stops later at Windsor Road the X2 has suddenly made up time and is now 26 minutes journey vs GNE who are still 28

So we race along to Low Fell The Cannon where the 21 now takes....

16 minutes!

But the X2 (which bear in mind doesn't stop again until Gateshead after Low Fell Cannon) now takes 18 minutes....

You should really catch the 29....that only takes 13 minutes to Gateshead (quicker than the others!)

Can anyone explain the logic that is Nexus?