If you are building an engine today (~2023), Professionals are not building Hydraulic FLat Tappet camshaft engines? Don't try?

David Vizard has a cam/lifter expose.
In it he claims to have tested many many cams and many more lifters, and as to Rockwell hardness and lifter crowns, they all passed muster; According to him, they are NOT the problem .... per se.
His analysis, IIRC, is that modern detergent oils and bottled ZDDP additives, are NOT compatible, and so you really need to install oils that are already engineered with the proper formulation..
having said that; He is also one of the guys who has eschewed FT cams; even tho,
he shows FT cams to be faster off the seat, and in his experience,
do not give up much power to rollers, especially as the lifters get larger in diameter.

Geez, guys; I figured/guessed as much, back in 1999, when I sped'd my engine.
My First line of defense back in 1999 was the engine oiling mods. the Second was a hi-volume pump. and Third was a 7-qt oilpan.
And after losing a FTH cam in 2004, the Fourth was to flood the top end with oil, to cool the valve gear, and Fifth was to drain the lifter valley onto the cam by drilling holes in the pockets between the lifters. In 2002 I raised the minimum coolant temp to 205*F, after re-engineering the cooling system.
Does it work?
IDK
But what I do know, is that since 2004, I only ever reset the lifter preload once., and it didn't take much; and I have been waiting ever since then, for the cam to die, so that I can downsize; but the little wheels just keep on turning.