Autoadvance is inhumane. Speakers should not be expected to have their timing down so well that every slide transitions smoothly. The presenter will inevitably be a couple of seconds off on every slide.
I am impressed how well you pulled it off. It is hard enough to write, memorize and deliver a 7.5 minute speech. Then to add a sadistic constraint like autoadvancing slides, that raises the bar. But you nailed it. Hats off.
Auto advance is going a bit too far. It's a recipe for mediocrity. Nobody can time transitions that regularly, and missing beats are ugly and painful.
I'd rather see a rule: Advance the slide within X seconds or it will auto advance. Then limit the number of words, or something, instead of the number of slides.
It's not that hard, really. If you memorize your presentation you can reliably get within a few seconds. Most of the transitions don't require pinpoint timing accuracy, anyway.
It's really common to overlook the amount of time that will be eaten up by applause/laughter, though. Don't forget to give yourself some breathing room for that sort of thing, particularly if your speaking format penalizes you in some fashion for going over time.
Another way is to impose a hard stop at the 7.5 minute mark. If after a yellow light and a red light the presenter is still yammering, cut off their mic.
It's definitely a different approach but it can encourage people to present in a way that flows more rather than a presentation that is broken up on a per-slide basis.
