Wow, I must be a really mean mom, and my husband must be evil. I remember our son in third grade kept squirrelling his finished papers away in his desk. At a parent-teacher conference the teacher told us how much unfinished work he had. He said it was done and in his desk. We walked over to the desk and, sure enough, there it was, done and correctly, too. The adults explained to him that if it is not turned in it is not "done." Dad and I then had him clean out his desk and throw it all away right then and there. He stopped doing that.
In fourth grade he was writing a paper. Holy cow, was it messy! 2 pages long, grammatical correct, well-written, but really messy. He recopied it 4 times that night, until 11 pm. He stopped being messy.
By the time he got into middle school he was swimming 2 hours a day after school, and he wanted to do his homework at the pool (with the other kids) during the 2 hours after school and before practice started. The caveat was that if the work wasn't done during that 2 hours, he would have to start coming home and going back.
He got it done.
High school - 2 hours of swim practice before school, school, 2 hours after school. One day he pulled dad and I into his room to show us his system. He had a whiteboard and he divided it into 2 sections, short term and long term, and he had prioritized his assignments by due date. Since he had so little time he organized himself.
I am a teacher, so I see the parental folder thing, and parents are always asking me to check their child's backpack for homework (no) and make sure papers get home (exactly how?) and I have also seen primary aged children figure it out and create their own organizational methods. The key is it has to be the kid's method or it doesn't work. IMHO when they are bailed out they do not see the value. When they are impacted by natural consequences (missing a field trip, not getting to order books, bad grade, getting a sandwich for lunch if they forget their money, etc.), then it is more likely to be important to them. The problem is parents are not willing to let them take the consequences and repeatedly bail kids out.
I am of the let them fall on their faces camp, but I really think it has to be early on when the lesson can be learned with the least amount of risk.
Oh, and I did help with applications!