It's a weekly event - every Wednesday night from April 18 through September 26 this year. I haven't been going nearly as often as Kevin but I will say that last week was exceptionally crowded. It was the first of the season and the crazy cold weather we've been having (and continue to have off and on) had turned at least for that evening. It looked like Main Street in Sturgis. It was absolutely packed.
We joked that in July and August when it's 90+ degrees it won't be nearly as crowded, lol.