Personally, what I liked about doing structured endurance training for cycling was that the results were positive / easy to quantify / and (over the duration involved - a couple of years) pretty much continuous (though obvs at a reduced rate over time). However, I can see how, particularly with climbers who have progressed through the grades on talent / movement / mental game, etc might find that a load of regimented activities that feel quite unlike what you actually want to do
I really don’t want to dig myself in any deeper speculating why it didn’t work.
Trying to hard, that’s what went wrong. Different to over training. I just wanted it to work and tried to hard at the expense of fun.