i have a theory on this but no way to prove it. when i had oil burning corolla (it started suddenly at 75,000 miles, but the initial burn rate was slow), i noticed that piston MMO soaks would stop oil burning for ~3000 miles (regular oil) or ~5000 miles (synthetic) before oil burn came back. I ended up doing those soaks every OCI to be oil burn free with synthetic oils.
so, my theory is, when piston oil holes plug up (with oil age and/or abuse), fresh oil (or better oil flush or piston soak) will clean the oil ring groove, but the rings will stuck up with the aging oil again if there is poor oil circulation (ie the plugged up oil holes, that part is irreversible).