How to reduce the duration of doctoral degree programs?

Aurelie Thiele has some suggestions:

... [I]f universities really want to shorten the length it takes for their students to get a PhD, they should implement mechanisms for students to switch advisors without the new advisor fearing retaliation from the old one, for instance, or for students to appeal their advisor's decision that the work isn't yet good enough. Also, many projects in science fail because this or that technique doesn't achieve the expected goal; students (and their advisors) currently see this as time wasted but such "non-results" should also be considered as important, publishable scientific advances, as they can help other teams of scholars by telling them not to go down that road. When all is said and done, the real issue should not be to shorten the PhD but to reduce the (currently absolute) power an advisor has over his or her students, or at least reduce opportunities for advisors to misuse that power. ...