As a youth leader, one of the toughest things I've experienced is having students remember events and then getting them there. Once they are there, you're golden.
I've tried to schedule things throughout the week and have had some moderate success with attendance. But when you get to the nitty gritty, an inconsistent schedule has led to mostly failure. The type of schedule I'm talking about is meeting for a small group on a Sunday, and then a Monday, and then a... you get the point. With this said, there's no consistency with meet ups and students are lost. Who's to blame them, people forget church is on Sunday too (that may be too much).
Wednesday nights and events that have been annual are what works. Anything in between, although it may be completely awesome, usually fall short on attendance.
With this said, a lessoned learned by experience is devote your time where its most meaningful. If Wednesdays are going to be your day, make them rock! Put time in where students are already...are.