My opinoin on a definition of Professional Development

I was recently asked to give my thoughts on a particular definition of what professional development is. Below is the website that the definition came from:
http://www.nsdc.org/standfor/definition.cfm

This is part of that definition:
"PROFESSIONAL DEVELOPMENT— The term “professional development” means a comprehensive, sustained, and intensive approach to improving teachers’ and principals’ effectiveness in raising student achievement --"

I would have to say that I agree with the majority of this definition. If professional development was actually based off the definition above then I think we as educators would be just fine. The problem is that somewhere between this definition and setting up the actual PD a couple of things usually get overlooked. The biggest one that pops out at my at first glance, is the word "sustained". Most the PD that I have ever be to is what I like to call a "one and done". Meaning, you go to a training on something you've never done before, and you have yourself a swell time learning about this or that, and at the end of the day your slowly starting to grasp the concepts and then the training is over. You get up, have the presenter sign your CPDU form so you can get credit for taking the training. You walk out of the room leaving most of the knowledge that received in the room you just came from. There very rarely is another training on the same subject, or any kind of follow up what so ever. If people where to take the word "sustained" in this definition seriously, teachers might actually get to retain some information they learned and actually apply it to their classrooms. If there was perhaps more than one training, or maybe even follow up training days it would make it much more of a possibility. I've never really understood how people expect you to really be able to grasp some difficult software program in a two hour training, or some new educational tool. That just doesn't seem right. I mean.... Teachers spend more time than that preparing lesson plans.
The definition itself is okay. In my opinion you can write whatever definition you want to, but it's the implementation of the definition that really matters.