Southern Iowa Speedway in Oskaloosa still runs on Wednesday nights. They're the only track that I can think of that runs a weekly show on Wednesday nights. I think they're moderately successful for an IMCA show (don't count the Front Row Challenge, that's not the weekly folk's deal).

I grew up at Knoxville, IL on Wednesday nights in the 90s. They now run one race during the county fair each year and have for a couple decades.

A special event here and there that you can advertise and anticipate is something totally different. Wednesdays are tough for weekly racing. You have to start later and on time to allow people to get there from work - and you have to end early to allow people to get home so they can go to work tomorrow. You have to be willing to cater to the diehards - and you have to have enough diehards to get you enough money left over when it's done to make it worth it. It seems like that's never the case.