Trainer difficult and the effect of "Variability Index" on difficutly

Hello, not the usual TD question.
I usually ride at 100% but did a bit of thinking and reading around. Understand TD and "watts is watts" etc etc.

BUT I wonder as to the advantage to a lower TD for undulating courses, as fewer gear and cadence changes would alter the power profile from a series of short intervals to longer efforts which are generally better tolerated (well for me anyway).

Zwift Insider terms this "Variability Index" and comments: "a lower Trainer Difficulty should generally result in a lower VI due to less resistance fluctuation. For many riders, this means the overall effort might feel easier at lower Trainer Difficulty since maintaining steady power is easier than doing intervals."

If physical gearing isn't a limitation, altering TD for constant effort (i.e VT) won't change much, but on the undulations of Titans Grove, reducing VI might be beneficial?

*So does the shrewd racer tweak the TD to the course? - I've not seen this tested!