This is documented as a Hacker Space Design Pattern. http://hackerspaces.org/wiki/The_Tuesday_Pattern

Problem

Every weekday sucks. You will not find any day when every hacker can attend a meeting. Someone always has an appointment.

Implementation

Meet on Tuesday. Since all days are equally bad, just pick the Tuesday. End of discussion.

we may open a thursday night edition... but overall, tuesday works well. there's always something going on in new york so it's all about determining your own personal priorities. if you want to get shit done, come to nightowls. if you want to see new tech start-ups presented and have the opp to meet 800+ interested in nyc tech, go to meetup..

There are some weeks in which I'd like to do both. I'm far more likely to go to something on Monday, Wednesday, or Thursday night than Tuesday, because there's a lot competing for my attention on Tuesdays.

fair enough. however, we can't please everyone! tuesday night is what worked well from the start... we're looking into more nights though...

That's pretty funny, everything in Seattle seems to happen on Wednesdays.