I don’t really “use” both at the same time. I do the TrainerRoad workout, and when I was chasing routes, I just picked a new one. I also did them up the Alpe to get the Tron. At this stage, I just use it to earn XPs (I want the La Vie Claire jersey!) and Drops so normally just the flat and/or short routes.
I don’t recall doing any events using TrainerRoad. I do like racking up the km’s for Strava too (I sync the Zwift rather than TR, with the comment being what workout). I accept it’s not really reflective but more reflective than the random TR km’s. And in fairness, it seems to tie in with the wear on the drivetrain. Also, the zwift calories are lower (?) which Strava syncs to myfitnesspal, and in these work from home times with lower NEAT, every little helps!
Now lockdown and a 5km limit is back, I’ve started joining a couple of Zwift Team Ireland events - Wednesday night group ride, and the Friday night race. But I obviously do them on Zwift.
It was always my plan to swap the “moderate” TrainerRoad workout to an outdoor ride or zwift over the winter. But after the Friday night race, followed by a few beers, I didn’t have the motivation to get up to do any of the endurance rides on Saturday morning (they’re generally 8-10am start here in Ireland). So I ended up doing the TrainerRoad workout later anyway. Virtual Beer Tasting/ Meet up this Friday after the race, so probably the same plan!