If that’s all them drivers drive, I wouldn’t think it too hard to keep it in their head to be fair. I know every crossing between Chester and Holyhead, but many drivers don’t, I don’t know every crossing between Chester and Shrewsbury as I have other means to identify locations on that route. I also have a fair few other routes I’ve gotta be familiar with too, and things can get too confusing, like water street in Manchester or watery lane near Wolverhampton. If you have a few seconds to think, you’ll get it right sure, but if it’s because of an emergency call…. The brain works a bit differently, prioritising other things. Easily confused.
This is where things like Risk Triggered Commentary comes in handy, saying things aloud as you get there or even pretending you are on your pass out, or giving a lesson to a trainee, helps. It keeps you alert at the time and keeps things sharp in your mind. Especially when you regularly do multiple routes and sometimes only see one route every couple of moths.
There’s many ways to help keep sharp but it comes down to the person. Do they have great recall or do they need to keep on top of things. I come in the latter category so I put the effort in to remind myself and test myself all the time. Many of my colleagues are much better than I at that stuff but I have my own strengths in other areas of the job.