Parasitic measurements with the new Fermilab g-2 experiment will improve the muon EDM limit by two orders of magnitude.
From here (a Snowmass report on "Charged Leptons").
Given that measuring some quantity in addition to the main target of the experiment's main objective doesn't necessary deplete or consume the main goal of the experiment, I'm not sure that "parasitic measurement" is really an apt description. But, surely this does capture some of the psychology of a high energy physics experiment manager's world. Then again, maybe the measurements of the muon EDM will be conducted by intelligent mosquitoes or tape worms.