I generally travel to tourism-based locations, schedule allows me to fly midweek, shoulder and low season, when loads are relatively low, limited number of elites. Success rate goes down when a larger group (presumably using miles) book in first, greatly reducing the number of available U seats.

With the exception of redeyes, I am okay sitting in premium, attempt to use GGUs on afternoon / evening meal flights, take my chances with the upgrade professor for morning flights.