I certainly don't believe this is the right attitude. No one is saying do 24/7 hands on training. But at least provide guidance . This isn't to say give the junior guy all the answers. Rather, push him in the right direction. Trust me, he/she will learn a crap load more that way and more importantly understand where they went wrong and why things did not work. The key is understanding. Without that fundamental knowledge, you get a copy & past dev.
"Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime."
I would rather have a dev on my team asking me for help, getting to the answer quicker, rather than spending 2 days on it, when it could have been done in a day. More importantly having the dev grow and learn. It's a win - win situation. Productivity increases, knowledge grows.
Personally, if I was helping a dev learn and grow, by my own experiences, that to me is very satisfying. You know... making a difference in life. Changing people's lives for the better.
But if you're one of those grumpy devs' that your juniors fear or don't want to ask you any questions in case they get some snotty answer back.. meh, I doubt you will ever be anything more than a grumpy, dev. (I left out senior, there, as I believe its a senior's job to guide, help and grow juniors. )