Workshops and training NEVER work: the disconnect between instructional design theory and practice

I know it's a bit of a negative title to the blog....but it's how I'm feeling at this very moment. As an instructional designer, I am schooled in the business of designing instruction that is aligned and designed to move participants from a start point to measurable outcomes. In theory, all of these outcomes should be met to a particular degree. When I design my courses, I find that I have the typcial frusteration of students who do really well followed by a large gap and then students who struggle and quit due to outside factors. In comparison, I see that my workshops (faculty professional development focused) follow a similar pattern, but sometimes the success rate (acheiving the projected outcomes) is even more dismal than my academic courses. Now, if I step back and take my instructional designer hat off, I'm not as dissapointed. I look at the faculty and staff that attended and see that though they didn't acheive the exact outcomes, they did move a step or two in the right direction. Often times, they acheived what they wanted out of the workshop. With professional development, isn't that what's truly important? So then I get to thinking. Why do I prepare these robust workshops with various outcomes....spend planning time....prep time....create handouts and websites...practice my content delivery...follow-up, etc.... If they truly are going to "get what they get" out of the workshop, why don't I just customize all my professional development attempts? How about picking several faculty a year to work with individually to customize their professional development endeavors. Measurable payoff for a small portion of the faculty, but less time spent on prep for a workshop in which most participants do not reach the projected outcomes.