I think if a solid cam is broken in successfully it doesn’t wear as much as everyone worries about. I think most will agree you don’t adjust them as much as you would think. Not that you shouldn’t check them let’s say if you take the covers off but even when you check they usually aren’t out.
I am in the same camp. There just isn't any empirical evidence of what causes flat tappet cam failure. If there was, then we would use that data for best practices and nobody would have flat tappet cam failure. My theory is that the Internet causes cam failures. We learned from the Internet that it was poor metallurgy in the cam and/or lifters or insufficient zinc in the oil. The Internet had solutions for us; boutique motor oils and extra specialized treatments of the cam and lifters. While this is a bit tongue-in-cheek, you have to recognize that even if you do everything by the book and then some (light run-in springs, boutique oil, immediate fire up and 20 minute break-in) you can still have a cam failure. Or valve failure. Or bearing failure. Or piston/ring failure. Or crank failure. Or rod failure. Or block failure. If you build one engine every year, you are in the statistical success, no problems zone. If you build 100 engines a year, yeah, you have some exposure to failure.
Solid flat tappets are usually pretty stable when it comes to lash. There were a lot of meek engines that came from the factory with solid lifters. Chrysler slant sixes come to mind. And a lot of OHC engines are solid tappets. You don't hear of anyone "running the valves" every couple thousand miles on those. You'd think someone was daft for doing so. I think a lot of checking lash is just looking for something ever so slightly off so that you can feel good about making something better. Takin' care of your baby.
Just rambling on here so you can protest my opinion.
