No worries, I didn't take it as criticism at all. Tools have gotten better, of course. However, I think the fundamentals haven't really changed in the sense t

No worries, I didn't take it as criticism at all. Tools have gotten better, of course. However, I think the fundamentals haven't really changed in the sense that accurate modelling is impossible outside of certain domains. The risk is that you can under or over-design thermal management. This is where experience with a design can be invaluable. As the design goes through iterations one notes performance, compares to assumptions and estimates and makes adjustments. We tend to work on projects that are highly constrained in terms of such things as allowable mass. And so, I can't just liberally apply a multiplier to estimates and call it good. We need to know. With time you develop test suites that stress things enough to achieve pretty decent test-based thermal data.