only allow as many Doctoral candidates as their are internship opportunities from the previous year. Problem solved.
I like this idea, but would modify it to be the mean of the last few years, maybe last three years. With small cohorts, there can be variation year to year. Influencing the variation is the fact that many graduate students are in their late twenties or early thirties and having children, and therefore may desire a more flexible schedule that delays completion of courses, dissertation, internship, etc. Programs should not be penalized for supporting clinicians with families, in my opinion. So there should be some way for accounting for this in the metric.
It sounds like the length of graduate school varies quite a bit by state and by type of program. In NYC, most of my colleagues from various schools were enrolled in doctoral programs for six or seven years -- I only know one person who applied for internship in the fourth year and he had a master's before entering his doctoral program. So five years plus a year of internship seems standard around here, and often I run into people who are at six years or seven years and still have not applied for internship. And I feel there are currently too many clinical hours needed before you apply to internship. Several of my former supervisors have indicated that in the past, internship was where you received most of your clinical training. Now it seems you need to have the equivalent of internship training before you even apply. I'd move it more to a medical model where the degree was granted (maybe in three years!) prior to the bulk of clinical training, which is then gained in a residency format.
Back on the parenting issue: For those seeking part-time internships (again, for example, due to parenting issues), non-accredited internships are the only option barring I think four choices scattered around the country. If you are going to do a part-time internship AND a part-time post-doc, this process can easily turn into a 9 or 10 year commitment. Not for the faint of heart, and realistically it is very often the case that a spouse/partner is shouldering the financial burden of this long process. What could be done? To improve timely graduation, offer high-quality daycare at the schools, mentoring, tuition remission and stipends. This could be encouraged by offering incentives via the APA accreditation process for programs to recognize non-traditional routes through graduate school.