During my Ph.D. I tried tracking down the reasoning behind a couple sets of assumptions made in non-uniform torsion of beams (e.g., twisting a beam with one end

During my Ph.D. I tried tracking down the reasoning behind a couple sets of assumptions made in non-uniform torsion of beams (e.g., twisting a beam with one end fixed). It turns out that they just kept the same assumptions from uniform torsion (just twisting the beam but with no ends fixed) without checking if they still held (they don't). All because nobody thought to check if the assumptions might be in conflict. The uniform torsion models go back to the mid 1800s, while the non-uniform torsion models are from the early to mid 20th century. So, it's been over 60 years people have been working with wrong assumptions.