As Kaze said, don’t overthink it. It’s a maintenance debuff that you keep up since it does it’s damage over time and it only really pushes out the rage you would’ve spent on one slam every ~18s which is worth the damage per cast tradeoff.
You’ll tend to open up by charging in, applying rend either through thunderclap or rend itself then going through the usual priority of abilities. Minor difference which you pick, TC only on bars enables 1 less keybind for a very minor inconsequential loss but also is still a gain anytime there are additional targets present.
It does also benefit from the 4p set bonus and other bleed dmg passives, it won’t do more than overpower on your overall with only 1 target present but it does have a place in keeping it up and gains a fair bit more value the more targets are present.