The window for voting seems a bit narrow…
I had assumed that the majority of people posting are doing so during the day, while at work, and voting occurs over the usual lunch period. In order that everyone gets a good chance to post photos and then has plenty of time for their assignment the voting can't take too long.
If this is a problem, however, for quite a few people then perhaps it be a bi-weekly thing with a week's worth of photos, voting at the end and then another week to cover the assignment. We'll see how this one goes!
And Mr_C, if you can only vote in the evenings then you could always vote on Wednesday night I guess!