Embrace the boredom! 
I do a lot of long sustained efforts and yes, they are mentally challenging and head is almost as important during them as the fitness but as they are quite hard they pass a lot faster than Z2
I find some comfort doing these long intervals as they are hard enough that my mind is fully concentrated in the workout and not wandering thinking about work and life.
I was saying that is more like racing where you’re struggling to hold onto peoples wheels and then when you get that draft you’re still going pretty hard.
Ok. I get it . . . practicing an element of racing (vs. focus on pure zone training).
I think racing is way harder than most any TR workout, though Basin (et. al.) is pretty good. TR is good training to be prepared for racing IME. That said, there’s a lot more to racing than your power profile. My limiter right now isn’t really my fitness; it’s my handling, specifically cornering and hairpins at high speed. Constantly having to chase the lead in a breakaway burns matches, and eventually I run out.
Summing up: don’t forget the other aspects of racing that can’t be addressed on the trainer… and to be frank, there’s only one way to get better at that, and that’s to put yourself in those situations! Learn by failing… then get back on and do it again.
Zwift racing, if you choose to do it, is even a step up in effort to real road racing, IMO. I just did a Friday night B event, and my “coasting” time over a 55-minute race was about 8 seconds. Most every crit or road race I’ve ever done the coasting portion is much higher. In that regard, Z is a decent proxy for race efforts, even if it’s seriously flawed in a bunch of different ways… but it is pretty nice to blow yourself up, get off the trainer and open a beer/brew a coffee.
Can’t remember if I have posted on this thread or not, but no its nothing like Mary Austin as other have pointed out (probably.) The last interval of Mary Austin is more like a TT?