It can be both.
If you get consistent good weather, you’ll probably be able to see most of the route as you go round it and navigation will be a piece of cake.
If its bad you might not be able to see the next 50m. What then?
If the cloud suddenly comes down (which trust me, it does all too often), you may go from knowing exactly where you are to not having a clue in under 5 mins.
Hence this:-
Your heading into the high fells. Map, compass and the ability to use them are a pre-requisite I would suggest
Always.
I was up there (NW Lakes though) last weekend. 6 hr ride, of which maybe 2 hrs I could see where I was in relation to other peaks & trails, the rest of it was either heavy rain or up in the clouds and I was checking the map repeatedly to make sure I didn’t make false turns on featureless and unknown ground – its very easy to make a minor mistake and end up dropping very quickly into the wrong valley on a bike, which can then take a long time to get back up to the top and correct.