Thanks Lodewijk for bringing this up.

I had several discussions in the past, mostly when it was about the
future of Wikimania, when I told people that Wikimania should have less
parallel sessions, longer sessions with more time between the sessions
and an "open space" as an additional track.

We implemented this idea last year at the WikiCon and I think it worked
well. The concept is simple:

* there are only 45 minutes sessions (with only one topic) plus a 15
minutes time buffer for sessions not ending on time, people changing
rooms, grabbing coffee on their way etc.

* this makes a schedule with a simple 1 hour grid

* due to the 15 minutes allowance in each session we skip any coffee
breaks - there is coffee break available at all times, from breakfast to
dinner

* instead, to give people some time to rest we added a 30 minutes break
where no sessions were going on half way between lunch and dinner. This
was not just a coffee break, it was meant to allow people to go outside,
catch some fresh air, have a nap or similar.

* there were only three tracks of talks (okay, for Wikimania I would do
up to five - but no more) plus workshops (real hands on sessions, partly
in labs) which were longer (~ half a day)

* there was one room near the coffee table with a pin board and an empty
schedule in front, where people could pick a card, write down a topic
and pin it on the schedule, to reserve the open space for a spontaneous
meeting - like the break sessions we were having at Wikimania

Example:
http://de.wikipedia.org/wiki/Wikipedia:WikiCon_2012/Programm/Programmraster

I know that my ideas are not welcomed so much, I have been told so many
times that it would be inefficient use of everyone's time to reduce the
program so much, that there were so many great submissions we really
must put into the schedule and that we need many, many parallel tracks
just to make sure we have small enough groups in each sessions to be
realistic.
Still, I am not convinced by these arguments.

* How many people could not attend sessions they wanted to attend, just
because they were in parallel / they couldn't make it due to something
else that kept them away?

* How many sessions were too short and the time was up when they just
felt that they were starting to be effective?

I am a strong believer that less is actually more. I would like to have
a less stressful but more effictive Wikimania.