No press conference should last more than 10 minutes, 15 minutes tops. Excluding Executive Branch Q&A events, long pressers simply serve no purpose. When I come across painfully boring speaker-thons, I assume that the flack in charge didn’t have enough credibility to limit speakers and check egos.
It also exposes a lack of understanding about why reporters attend press conferences. For instance, 9 times out of 10, a TV reporter will prefer a one-on-one interview with a speaker off-podium for their ten-second sound bite. The podium shot may only serve as b-roll to introduce the subject. In this case, the background and set up are more important than what the speakers are blathering on about.
In the case of multiple speakers, I recommend a two-minute cap. This way print and TV reporters will be introduced to all of the speakers and gain an understanding of their unique perspective or personality. Reporters can then pick and chose follow up questions and interviewees to best serve their audience.
All this being said, some people will tell you that checking speakers is impossible. So I offer you this example below. A 7 speaker, 15 minute press conference that we did a couple of weeks ago to press Congress to pass the RESTORE Act. Do the math.