I recall a report posted on the forum about oil starvation on a modified Fist out of GB at the 'Ring couple years ago. Crank bearing{s). There were no warning signs, failure diagnosed after engine teardown.
In my opinion the buckets over valve stems/springs does make it a solid lifter setup, the buckets themselves are the "shims" used to adjust lash. In contrast to my 1.6L Lotus Ford TC, which also uses buckets but with solid shims beneath, so adjusting valve lash means pulling the cams, pull buckets, changing shims, put it all back together and measure again. Big pain to get right, but bulletproof once it is.
I have no idea how Ford controls wear in our valvetrain, maybe with modern materials there is not enough wear to need the shims.