The Raceways I frequented during the Sixties were usually open 12-15 hours daily with customers waiting at the doors early, especially the AMCR Tom Thumb Raceways.
A waiting list with a delay of 30 minutes to get on a track was normal.
Track maintenance was done when the Raceways were closed because doing it when open would mean shutting down tracks and losing revenue.
The Raceway that was located in the Mall I am in now grossed at least $50,000 a month for 3 years (one of my friends worked there during the summer and saw the receipts, I was in Korea at the time). The owner shut it down and bailed when revenues dropped under $10,000 a month, saying it was over. LOL
The big 8 lane track fad was short-lived but the participation and money made by those who got involved in the business early was amazing.
All you have to do to get a feel for the money and the market is look at the cars and kits that were being mass produced by companies like Cox and Revell...really big bucks investments.