In my experience touring, it’s really easy to edge above a HR zone without feeling it, even while chatting and taking it “very easy” – I think the lack of impact on the uphill glide makes this so. Once I’m above the target zone, it’s hard to throttle back and find the right pace. I have to dramatically slow down, let my heart rate settle, then reacquaint myself with the desired pace to match my intended HR zone.
Perhaps over-simplifying it, but if the goal for the workout is to be in Z1 or Z2, you’ll have to slow down to achieve that. It’s also worth ensuring your goals match the groups for the day, if you’re aiming to do intervals while the others are going for a quick steady state tour, those could be hard to make compatible.
Just some thoughts.