After years of playing 3E through 5E (yes, I got back into Classic around 2006, but have still played the other editions), I've kinda gotten used to the idea of each player making their entire suite of actions at one time in the combat round. Move, attack, other miscellaneous actions all resolve at once, before others act.
And even in Classic, using group initiative, I've often defaulted to letting the players act in any order they choose on their side's turn, telling me everything they do at once. It's easy to go around the table and just adjudicate each player's actions one by one.
Recently, though, I've been trying to run the combat round by-the-book. And in Classic D&D, this means the sides in combat each act according to the order of actions first laid down in Chainmail.
Move. Missile Fire. Magic (Artillery in Chainmail). Melee.
It didn't seem to be a problem for the past few sessions, using theater of the mind. But yesterday, I had a small crumbling castle full of orcs and a troll that the PCs were exploring, and I wanted to use a tactical battle map since the orcs had chances to surround the PCs (although clever play with the first cohort encountered made that moot). Using the map, and dividing up movement from other actions, especially in simultaneous initiative rounds, really seemed to mess with the players. Lots of comments like "Oh, is this still the same round?" and "I move here and do X" - "You already moved."
So I'm wondering. Part of me likes the phased initiative system. But part of me likes a more open and less restrictive system.
Something to discuss with the players, I guess, but I think I may just ditch the phased combat round and go back to just going around the table and asking each player what they do each round.