Mass however has little to do with tracking. And correct track has everything to do with balance as the effective diameter of the rotor changes with track. Make a blade fly higher or lower than nominal and the effective diameter reduces.
Of course, if you have a heavy blade, you can put it out of track a bit to bring it's effective balance point closer to the head center point. But then you might get into vertical issues.
There is no dark art to RTB. Just experience and observation. Remember your adjustments and remember the effect they had on the RTB. If it isn't going where it should be, back track (no pun intended!) and see if you need to adjust your clock angle. You might be getting the movement you need with your adjustments, just not in the right direction!
Good luck with the 412. They're a prick to RTB to begin with. Talk to Abu Dhabi Aviation, they have (or did have) the best 412 balancing notes around. Oh and don't forget your clock angle corrector. You'll need it on lots of 412's! And re-torque the head after EVERY RTB flight if the head was just put on. The hub has a habit of shifting and ruining your RTB. And pair opposite blades with similar hours as the blades get more flexible as they age.
Fricking 412 RTB. Yeesh.