(Not) Pro tip:
Reduce the wattage at which you’re doing threshold by 5 to 15 watts, whether you’re doing steady state intervals or over/unders.
Then work your way up gradually from 3 × 10 to 3 × 12 to 3 × 15 to 2 × 20 and beyond.
I used exactly this method to get to the point where I was able to do a ride with 1 × 26 and 1 × 56 at 98% of FTP.
Better to work at 96% to 99% of FTP and get 99.5% of the benefits than to work at 100% to 103% of FTP, die a thousand deaths, and limit your time in zone to a fraction of what you could be doing.
Also, and finally, try to use power to calibrate your RPE so you can feel your threshold on any given day and ride at it.