Have you ever wondered why the engineers don't come and ask your advice before they waste a couple of months?
I'd much rather be known as an approachable and helpful engineer who juniors can ask for advice, even if it means I'll never be known as a 10X engineer.
But the ones who don't are more difficult for me. I think some might be shy or unaware things can go better. The most trouble I have is with the really stuborn who don't want to learn, and think they know it all.
I try to avoid these engineers as much as possible, by hiring the ones I think are eager and willing to learn.
Where do you draw the line?
How often can a junior approach you before you grow tired of them constantly asking you for help/guidance?
The hardest problem with mentoring juniors is that most companies don't recognize the work put in. Still too many places judge purely on your direct work-in to work-out ratio.
Personally, it would depend on if they're learning from my guidance or not: if they keep coming back with the same problems I'd get frustrated that they (seemingly) weren't attempting to learn or improve. On the other hand, it they usually come to me with new problems they've encountered and gotten stuck on, I don't expect it would bother me nearly as much.
Of course, IRL it'll probably be somewhere in between.