Ditto - I have nothing left after leg training. I saved cardio for *off days*.
Honestly, I think it may prove more degenerative or possibly catabolic.
Save that (added) stress, the energy for recovery the next day(s),
even with advanced supplementation - AAS in my case.
25 years of bicycling taught me (about my body at least) that I can do
1:15 - 1:30 leg (cycling) routines. But, doing 45 to 50min weight training
time length is ideal, to (add or) aid the stress/recovery process.
For me post weight training cardio (added stresses)
which may tap this critical recovery resource.
Each of our goals ARE different, for me (now) strength, size and shape.
Not primarily, endurance at this point in life (at 45).
Was endurance trained most of my life.