[dirtyid]

IIRC you can generally handle 120-140% weight of concentric with eccentric. The issue is HEAVY eccentric for advanced lifters is extremely taxing and fatiguing on body and is suboptimial in how much it can eat away at overall routine volume / practice by pushing body into recovery debt that ultimately drives progression (for many). Singles with 90%+ or supermax (over 100% 1RM) eccentrics when programmed are done with very few reps (often just last rep to pins/safety, anything over handful singles per week is considered machoistic). Otherwise it's reserved for tempo work i.e. 4010 or 40X0 (4 second down, no pause at bottom, 1 second up or X explode up, no wait at top) with relatively light %s that doesn't fatigue for technique work.