As we all know when a plane is on the ground it's not earning money so I guess they have used BHX as a trial and like I've said had a taster.
Commercially, you don't do "tasters" as when you decide to terminate the "taster" then you have effectively pee'd off the customers to whom you have sold seats on flights that won't operate. Even if the seat is dirt cheap, you won't sell to the disgruntled passenger again.
At another level, an aircraft sat on the deck loses less cash, that one flying and not making a profit. That's why Ryanair lay up so many in the off season.