Dr. Kaveh Azar quotes1-2 Quotations of 2
I advise engineers to start by performing first-order calculations to see where a heat-transfer problem lies. You can quickly estimate the heat-transfer answer to within 20 percent to 30 percent. After you have a first-order solution, use computation or experimentation to perform another, independent analysis, but do not use results from the first-order solution as boundary conditions. You want two independent answers.
~ Dr. Kaveh Azar