The question is phrased with few options on purpose. Did you use a UV/haze protective filter on your EF 70-200 f2.8L IS (I or II) during its most recent use?
The aim here is to assess filter use among a narrowly defined group. I have avoided asking do you "generally" use filters as this can lead to subjective "calibration" of the response to suit attitudes that are deeply held but not practiced.
Because ultimately, actions speak louder than well thought out intentions. We all know the usual arguments for and against using UV filters that proponents use to support claims. Some fall back on specific lenses, where IQ may suffer vs. need to protect the front element, and needing it to complete weather sealing etc etc...it is frequently a slew of compromise explanations.
Let us try and gauge what we actually do in practice by taking a lens owned by good many, granted not all; and of 'relatively' decent $ value; with consensus on high IQ (that could arguably be degraded by a haze filter). To increase the sample size, either of the 2.8L IS versions are ok. This lens choice also hopefully ensures we aren't sampling exorbitant superteles or the lower price range lenses; but, something narrowly defined, commonly possessed, yet valuable.
In voting, please let only your actions speak. No "oh I could have" or "oh I wish I had" answers... No fudging...simple question: did you have it on during its most recent use?