The issue of lower fares sometimes depends on timing, particularly when you are about to make flight reservations or even when checking the option of upgrading seats. Tuesday and Wednesday mornings in the week are historically Cheapest day to fly business class. These days tend to be the cheapest days of the day on which the business class fares are adjusted to have premium seats occupied by the airlines. The given pattern can be useful to travelers, who can make a group booking or make or cancel a ticket decision. https://askforairlines.com/blog/cheapest-day-to-fly-business-class/