There are a few airlines that will do ten return trips as a kind of carnet. Some airlines sell these directly, but I think most go through a reseller like OptionTown.com. Unfortunately the pricing isn't very good*, it's essentially the average price that you'd expect over the week, with a bit of a discount. Worse, although the tickets are supposed to be flexible, changing them is typically a pain that requires calling a travel agent at least a day before.
Regrettably, your business is just not that interesting to most airlines. The very smallest airlines may offer you a discount if you are buying a few seats per day every day. A network airline won't be interested in distorting its price-demand analysis until you are offering to buy dozens of seats per day.
In normal circumstances your best bet is to buy about eight to four weeks ahead on whatever looks the best price.
* In the current situation you may find less orthodox ticket purchases do offer a good deal because airlines have forgotten to update prices there. Demand at the moment is soft, but most people who are travelling have to travel, and supply has become restricted, so paradoxically some airlines are in a strong position to charge high prices to those who must travel. Shop around.