I read the Zwift Insider article posted by Aaron, and according to that article, I “should” be seeing a 6 watt benefit on the bike frame I have.
There does not appear to be any quantitative tests of the DT Swiss ARC 1100 wheel set to define any wattage benefits from using those wheels. There should be, considering Zwift claims that they are the second most aero wheels that can be used in game.
Even ignoring the wheel set, my argument still stands: if the upgrades have provided marginal gains, I should realize those gains every time I ride in Zwift. Doing pace partner rides with Maria as I routinely do, my average wattage for a ride should now be 159-162 watts, not still 165-168 as it has been in the past. If my bike now has a 6 watt advantage, and I am riding with the same average wattage with Maria or any other pace partner, over the course of the ride I should be slowly riding away from the group. My pace partner rides in Zwift are typically 25-35 miles (40-56Km). Over that distance a 6 watt advantage should be seen in my average power output for the ride, the average power for the ride should be lower than it was before I got all five upgrades.
I do not buy the argument that the advantage is only realized in very specific riding situations. Zwift might have modeled it that way, but in real life, any advantage that saves wattage will apply in any and all riding conditions.