Attendances have been dreadful on Tuesdays in the past and the management are naturally keen to avoid fixtures that end up costing them a fortune (understandably) which is why we avoid weekdays in general.
Available dates for Sundays, Fridays and Bank Holidays are very limited due to other events at the Showground with an increased fixture list this year not helping at all.
Doubling up clashes, overseas and world championships etc cause immense rescheduling problems as you will appreciate when involving 14 riders associated promoters and team managers.
I have recommended several times that the Premiership and Championship run on different race nights, it would end the doubling up problems overnight.
What evidence do you have that the BSPA listen to anyone.