The best solution is to follow Glenn's advice---once you've done a full trace exercise a couple of times you'll know what you're actually capable of achieving and adjust your program accordingly
For example, we have in process waste containers-however when we have a really bad run (item specific) the waste containers may overflow into the drain and we have no idea how much we've lost (ag commodities too many variables) so perhaps today's trace yields me 99%, tomorrow may only be 85%
Once you have performed a couple of trace, you'll have actual data into where you are losing product (does your product shrink in the warehouse, does it absorb moisture, how often are FG verified for quantity/weight etc.) Then you can adjust your procedure/program with an explanation of where the variance to 100% is coming from