I’m 46yo and I’ve been on HV plans for 3 years (TR user for 5 years). I typically train 10-12 hours during winter and 11-15 hours spring through fall. IMHO following TR plans blindly is a recipe for disaster. I’d give the TR plans a “B” grade at best (up from a “C” grade now with ML). I strongly disagree with TR’s marketing that it’s the right workout every time. It is not!
You are still your own coach and you must alter the plans to fit you. For starters, it’s almost never a good idea to do SS on Sundays as prescribed (exception is usually SSB1 coming from an off season but forced to ride the trainer). I strongly disagree with TR and ML seems to have only made recommendations worse for Sundays. This should always be a long z2 (MV and HV plans).
All z2 rides should be between 60-70% and the ideal spot is usually 65% (moving up/down based on RPE). TR routinely schedules my z2/recovery rides too intense (Wednesday and Fridays). I always have to swap out these z2 rides for an easier version.
Saturday’s workout should be a flex day. Do the workout as prescribed if you’re capable or swap or to a long z2 if fatigue is high. I don’t do this often and when I do it’s usually at the end of the season, but that should always be a viable option.
Lastly, use workout alternates to shorten / lengthen workouts based on available training time and fatigue. Also, if a workout structure looks unappealing or too repetitive based on workouts you’ve recently done.
IMHO people need to be better coaches to themselves. Doing so has brought me from being burnt out using MV plans years ago to now adding volume to HV plans. So I’m able to add volume and fitness improving year over year as I age.