In Netherland they're neither in the weekend, nor a day off. But voting stations are open really early until pretty late, and usually within walking distance, so everybody generally has a chance to vote.

If not, weekends and days off aren't a great fix either, because some people have to work on weekends or when other people are free. Generous hours and the ability to vote early or authorize someone else to cast are better to give absolutely everybody the opportunity to vote, I think.