you never know everything. learning is a good thing. if you dont learn something every day, you wasted a day.
as for schooling....if i am looking at an application (which i am doing this week....) and i see one dude worked for Pep Boys/Merchants/NTB/Sears and one is a graduate of a training program and has a little experience, i am gonna hire the one that went to school instead of the other one.
from what i have seen, there are few damn good techs that work for those places. yes, there are some good mechanics there sometimes (one of the best driveabilty guys i have ever met taught me a shitload at Pep Boys) but the stars will go on to other places most of the time.
the main thing is that one person will take the initiative to get learned, while the other will work. granted, i have seen some morons come out of schooling....but most were pretty good.
then again, some of the best mechanics i have met cant read also...