It all depends on the player, the strings used, and the bass: Wood varies, some require more attention over time than others, though generally the older a piece, the more it tends to stay put, though there's no absolutes with wood.
Alembics tend to stay put set-up wise relative to a lot of other brands due to the laminated necks, and the 1/4" ebony fingerboards are plenty 'reinforcement' to the double truss rods.
I tend towards a relatively flat fingerboard, so for me, around 10 to 12/1000ths relief (this is measuring the gap with feeler gages) is where it feels right to me. The only real importance is how it feels to you, there is no 'right' answer. I've been doing my own adjustments now for so long, I'm very used to what those numbers feel like, and my hands will tell me when things are starting to creep away, and typically, my Alembics required very occasional attention to this, they were just very stable.