I use it in all Buick engines, flat tappet and roller.
A hydraulic roller has about twice the spring pressures vs. flat tappet, the very small roller bearing in the lifters and rockers are subjected to extreme loads as most owners install them along with other items for more HP which also means higher RPM's.
Small price to pay for good protection, especially in a high performance engine.
If you use a performance oil like Brad Penn or Joe Gibbs, not needed there.
But our turbos push lots of contaminants into the crankcase/oil, so I prefer to use a less expensive oil with ZDDP Plus, since it is more cost effective when the oil is changed often like it should.
In the long run, less expensive clean oil is much better than premium dirty oil!