I do remember that they had a very hard time measuring fuel economy accurately enough so they had to find a significant effect just to pronounce anything. They also were not above erring on the side of safety if they felt they might be seen as condoning something of questionable safety.There was an episode of mythbusters that addressed drafting, and while they were using ICE vehicles at the time, the summary that I remember was basically that you have to get dangerously close to have a significant effect.
And they didn't have TACC. I'll wager they could do the tests again with Teslas and get real results, where they could control following distance and measure instantaneous energy usage.
Personally, I prefer good planning to questionable catch-up tactics that you should have planned around. That said, I have had to draft on a couple of occasions -- once where there was a power blackout in the desert and I had to limp to the next SC, and once travelling between two destinations where I really didn't want to stop at an RV park to make it, so I was as frugal as possible from the outset. Both times TACC following set to 7 behind a truck going under the speed limit.