I have both buried and potted them deep but not filled that back
corner of the pot. Making sure I have added extra bark mix to
the front corner. The Brassias are the worst for me. Neither
way has added to the rot in our collection.

I think a try at combining the two works best. Push the old bulb
down - but don't fill tight around or over it. Then put extra
mix in front of the new growth, or under it.

That's what I do as well. I build the mix higher around the new growth.
Also, if the back bulbs are shriveled or leaf/rootless, I just cut 'em off.

Diana