Indeed, but not without risk. If no acceptable routing comes up you are stuck with cancelling the ticket you cannot use and paying the change fee. I am about 50/50 of finding acceptable SDC's, all depends on the market for the particular segment.

If OP has a large enough redeemable mileage balance another strategy would be to buy mileage (saver) award tickets if available (most likely standard chart though), and cancel them at T-15 minutes if you get the SDC you want. Free cancel/redeposit for 1K and Plat, $100-200 fee for others. At least the fee is likely smaller than the upcharge for higher fare class confirmed in advance., but the cost of standard award miles might be more than someone wants to spend.