Is there a good reason why the gear cables on my bike would have been routed with the rear mech cable on the NDS & the front mech cable on the drive side at the headtube, crossing about halfway down the downtube?

I thought most bikes were like that?

Don’t honestly know; sounds like it’s not just mine, then.

Lots are like that. I’m sure it’s something to do with stopping loose cables hitting the frame or having less water drip down the inner? I’ve certainly seen someone try to justify it on a technicality.

so your rear shifter is on the right and front shifter on the left so the cables wrap nicely round the head tube.

I hate cables that run up the same side of the head tube as they are mounted.

Obviously as the RD is on the drive side the cables need to cross.