GETEM and NETL both calculate their O&M labor costs using a heuristic to estimate annual manhours required for a power plant and then combine those with an hourly rate and overhead percentages to estimate O&M labor cost. However, the NETL labor cost is 100% greater than the GETEM cost. This is due, in part, to NETL having a 20% greater base pay rate than GETEM. Both NETL and GETEM provide detailed bottom-up estimations of O&M labor costs, however, the NETL labor costs are more in-line with other estimates. We can extract from this comparison the cautionary tale that detailed bottom-up analyses often look convincing due to their simple, straightforward display of facts, but the result must ultimately be validated with comparison to other models or data.