the longer the time period the less reliable the payback method. Is that a true statement? If so, why? Think about the time value of money. If we have a ten year time frame versus a three year time frame will the present value of an inflow in the latter years will be more or less accurate? In addition, think about how this relates to valuing a short versus long term debt security.

With that said, honestly, are the more accurate methods (NPV and IRR) really that difficult?