In my application it was a very mild Comp Hydraulic flat tappet with a stock push rod. In the past I lost a couple of Comp pushrods to a Indy built 505. Tried a Mancini one in a mild 383 as well before the owner gave up and swapped the engine to fuel injection.
I do feel like a spread sheet of data among those of us that have lost them may help build a trend. I'm seriously starting to think it may be fuel pump related in either clearance/preload and/or spring load of the pump. I remember in my younger years the smaller bodied NAPA pumps never gave us any issues, until the manufacturing went south and the lever arms started falling out and into the oil pan. After that I went to the Carter units. never had a issue for some years (luck)? and then recently seems these pushrods just don't last. Unfortunately all my failures except for the 383 were on fresh engines, so who knows.