At least in endgame. Which I'm assuming is what the OP is talking about considering he was talking about AD + SS = burn.
Its not a waste in boss fights. Typically the skill has no CD but cannot be used in combat. R/M gives it a CD but it IS usable in combat.
After your shadowstab/low blow, you wanna use Premed to power up Wound Attack for a high triple crit chance.
+ 2 procs from those. THEN IBD running. All those have such a high possibility of taking the PreMed. Sure, ET wouldn't be bad. But the OP wants to get the WA on AD+SS. Even diyce'ing is unlikely. Waste of time.
This post has been edited 1 times, last edit by "Magío" (Jun 2nd 2017, 3:02am)

This post has been edited 2 times, last edit by "Bafar" (Jun 2nd 2017, 7:22pm)
I still remember Bleedingblak saying he used to do this. BUT that was like 2 years ago when AD was a whole 10s long. Bosses took around that long to die. Now they take way less than that with only 3s of AD. Also targetting Warlock/Mage SS wasn't as prevalent then. So getting that 40% boost on AD back then was, STILL MAYBE, worth the risk. I say maybe because you have to consider the lost damage in white hit procs from Enchanted Throw from untargetting... Not only that, Illusion Blade Dance is STILL going... so there still a fair chance that will take the PreMed instead of the WA. Basically what Bo said.
Target self to stop auto attack
Pop Premed
Retarget Boss & WA
Profit?