Testimonials for corporate academies: running a paid pilot

I'm opening a small working session for L&D people who are trying to get learner testimonials out of a corporate academy, not a consumer course. What I've found is that completion and testimonial collection are the same problem — people who finish have something to say, people who drop out at module two do not. I'll walk through how I've been testing collection points at the moment of completion rather than three weeks later, including the one that flopped. Bring your own structure and we'll look at where yours leaks.