The difficult comes when a slight change in rules come, especially when it’s a change to something you have been repeating and memorising for years.
When I passed out I could answer anything, as I’ve been driving a while now there is some stuff what I would consider vital that I know and some stuff that I have written down and can refer to. I still know it but not quite as quick to answer as I was when I passed out.
Often drivers have cheat sheets, simple things like distances, speeds when running with certain defects, bell buzzer codes and things like that, that if necessary can be quickly looked at. But as others have said it’s all up there, just sometimes if it’s not been used in a while it needs encouraging out of the brain.
It’s handy to pick up the rule book now and then when on spare as a refresher but it’s not always the easiest thing to do especially when tired.