I used a full bottle of GM EOS to break-in an engine years ago, and also add about a 1/4 cup or so of EOS in with the normal oil change since then. This was during the time frame where oil manufactures were removing the good stuff from oil so I figured some additive just in case was better than none at all.

It's a daily driver engine with a real mild camshaft fwiw. If was something stouter for a weekend fun car I would look at a more performance oriented oil without having to use an additive most likely. Old car driving season here is only so long and one oil change per year will do just fine even if the oil and filter was more money for the good stuff.