This is the idea of lightning talks - all inclusive, first come first served (although we can of course organise so that similar talks aren't one after the other, say). Bad speakers or uninteresting topics don't last long, so you know something else will be coming after.

If we do 2 hours of lightning talks, that makes 25 speakers - if we over-flow then we can of course filter, if needs be. But I guess we're not going to overflow.

Dave.