While each of my converter boxes has a dedicated headphone output w/volume (I'll often use that if it's only me and I'm using the DAW)...I tend to use my dedicated S-Phone headphone amp/distro box, which has 4 channels, and can also accept Aux inputs...and then I also have multiple Redco Little Red Cue Boxes, each which have 4 headphone outputs w/volume.
If I need to get real crazy with separate cues mixes, I can always do that through my console, which have 8 Aux busses.
So I have a lot of flexibility and can cover a good number of headphones with personalized mixes if needed...but I rarely need to get that crazy.
At most...I'm maybe adding some additional Aux input to the S-Phone if I need to add or "filter" out some of the mix of a given cue mix for one person or two. Whenever I've used multiple headphones in a tracking situation, everyone is mostly OK with one global mix.
If you offer too many variables...everyone will want them....so keep it simple, and usually after a couple of passes people are set with their headphone mix. It's often just a matter of the overall level being adjusted for each person, bot not so much a need for personalized cues mixes...except when Madonna comes over!!!