My AD&D campaign uses initiative rolls every round. I occasionally pay attention to them. Yes, there are predeclared actions, and those actions often make the dice irrelevant.
The trouble is that the initiative rules are really complex.
A couple of months ago I ran some AD&D. I tried to run the initiative rules by the book, and I found it easy enough, though the rules are complex.
I think we did it more-or-less like this:
(readied missile weapons would go here but this never came up... I don't think)
Missile/melee attacks go here; if you have more attacks, your first one goes first; otherwise check initiative to determine who goes when
Movement (including movement + missle/melee, which I'm pretty sure is a house rule)
Spells & spell-like effects (activating rings, drinking potions)
Charge attacks (with longer weapons going first; if you both have long spears or something, then you check initiative)
We'd declare actions for the round, then roll initiative; that roll would only be checked if it came up (who shoots whom first, etc.). Initiative generally didn't come up that much, which I found to be pretty nice.
I'm pretty sure we had spells going (near) the end at one point, which was a mistake I think we fixed.