In reply to dangle:
I was on Tryfan North Ridge last Friday. Had a been up it several times before, but being on my own this time, and with perfect weather (so with no one else/adverse weather to worry about), I had time to reflect on a few things.
Firstly, the route-finding isn't necessarily straightforward for the inexperienced - I encountered a number of groups asking whether 'this was the right way'. Typically, they'd have come across a move which they'd decided was too hard (even though it was probably on the right line), and had contoured round in search of something simpler, but ended up trying something harder. The advice I've seen in some guidebooks is 'stick to the crest' but to be fair, it's not always clear where the true crest is, and indeed, the crest doesn't always have the easiest moves.
Secondly, there are options on there which are much harder than Grade 1 - I was searching these out, perhaps, but just because they're avoidable doesn't mean people don't end up on them.
Later on the walk, on Bristly Ridge by now, there are a few sections (such as the downclimb into the notch) where, if you've got to them, you've got little choice but to carry on.
I think given all this, the description of Tryfan as Grade 1 needs to be caveated. I think it leads to overconfidence - thinking 'this is only G1 - I should be safe' - where in fact the person may have wandered onto far more serious ground.