I was fixing a mirror reflection on a bus window render and a retired train conductor sitting behind me at the library cafe asked why my grid lines kept distorting. He grabbed my laptop and rotated the whole object 45 degrees on the Z axis, then said 'checkerboards only line up when you stop fighting the perspective.' It fixed my material seams in 20 seconds after 3 days of guessing. Anyone else get random real-world advice that solved a Blender issue on the spot?
That line about checkerboards only lining up when you stop fighting the perspective hits home. I had a similar thing happen with a tile floor texture that kept showing seams no matter how I tweaked the UVs. A guy at a print shop told me to rotate the whole plane 45 degrees and then scale the texture down so the repeats didn't land on the same pixels, and the seams just vanished. Turns out the fix was never about the material settings, it was about how the pattern sat against the camera.