Allow timed slides within an untimed presentation.
Useful for presentations that include a "Q&A" period or another time when the presenter needs to focus solely on the audience, but would like to continue showing pictures or diagrams at the same time.
It would be an added option from speaker view, which allows you to turn on the auto-slide timer in the middle of a deck.

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ronney singh commented
Everybody has that feeling when the audience is a 'step-up' from your comfort zone. The only/best way to eliminate it in the long run is practice. But a few points that may help:
The audience either doesn't care, or is on your side, i.e. either they are not listening (which mostly has nothing to do with you) or they are interested and therefore want you to succeed. They aren't hecklers in a comedy club.
Know the first minute of your talk completely by heart, know how you will end the talk and know the order of your slides. Once you got the ball rolling it usually isn't that bad (at least for me).
If the size of the audience is a problem, unfocusing my eyes so they just become a large blurb, or looking slightly above the audience (or an empty spot) can help. The old advice is imagine they are naked, but I would go with stupid hats instead if you take that route.
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Kevin commented
I have the same need -- ideally I would like to set timer on a slide-by-slide basis. For instance, I might have the first 30 slides an a four second timer, have slide 31 with no timer so I have to manually forward when I am done speaking about it, and then have slides 32-45 on a ten second timer