In every case where I’ve had a conversation with someone about the pushrods falling out........ it’s always been at start up(and was running fine when the engine was shut off)........ and was involving a hyd lifter(the motor we had here with this problem had a very mild HFT cam).

I have not heard of a single incident where the pushrod fell out during start up when a solid lifter was being used.

Some of the people I spoke to that had it happen multiple times(on random cylinders) solved it by swapping to solid roller lifters being run with very tight lash settings.

The deeper the “cup” is(whether in the rocker or the pushrod), and the more preload you run......the less likely it is you’ll encounter this issue.

Also, hyd lifters with less plunger travel will be less prone to have this issue.