If you will be flying mostly on Tues and Weds then your chances are much higher and if you fly in mid-range fares as in W or higher then I would gamble and say you will clear at least 50-60% of the time...

Be smart on which flights you pick, avoid the 752s, and check the F cabin/Y cabin elite sections to see how many seats are occupied... I know seat maps are not a positive indicator of how many people are actually booked, but it gives you an educated estimate of how many people are booked...