Chapeau for having the mental toughness for those workouts…if I can get outside with friends then 3-4 hours z2/3 is great - if not then 2 hours SS it is - can’t face more than that on the trainer - I did McAdie today - going to do Tallac +3 tomorrow as we have another storm - 3rd in 3 weeks in the UK - although this one has a Spanish name!! - As mentioned above most people didn’t do the v long turbo sessions in the past so the 2 hour SS rides replaced it - I suppose I will still get a 250 TSS weekend so all good but I would prefer not to always get it staring at my tablet - effective as TR is!
It’s other way around in my case – used to be on very stressful DevOps job. Long rowing sessions helped to clear the mind and made me very calm. Took the meditative approach along to cycling world, accompanying fitness is just a bonus.
Or maybe i’m just long term dopamine and endorphin junkie, can’t get my fix so easily any more 
It depends a bit on the races you are planing to take part.
If they take you longer then 2h, you will benefit a lot from the longer z2 rides.
But even if they are shorter: more variation in training is alway a good thing and there are adaptations to harvest, for which no shortcuts exists.