An ex-colleage, travelled London-AMS quite often. He always knew what U2 flight he would travel out on, but could catch one of a few return flights in the afternoon.
His solution, book all of them. The total (if booked a reasonable time in advance) was still cheaper than a day return on the network airlines.
He also went after a refund of the taxes paid, until the airlines put up their 'processing fee' to a higher amount than the refund.