What necessitated the use of a spreadsheet? Is it the sheer number of combatants? Some other complexity? Admittedly, in my own group the party has rarely exceeded about 20 members, including Henchmen, Familiars, animals, NPCs, etc.
Can you give specific examples?
I generally let PCs run their Henchmen as they see fit, only intervening based on significant conflict with a given Henchman’s personality and goals, or the failure of a Morale roll (which I believe has only happened a very small handful of times; the party tends to lavish their Henchmen with rewards to keep them loyal). I’m curious as to what you’re doing, as I often have self-doubt about the degree of control I allow my players over their longer-term Henchmen…
One huge piece of relevant context is that we’re playing online, and all five players have small children in and out of the background. With over twenty combatants (last combat was over thirty separate lines even running groups of hirelings and nooks as single lines), it’s imperative for me to be able to keep things on track and moving forward.
Regarding henchmen, I tend to gravitate towards your camp for simplicity, but I struggle conceptually with the hive mind that is essentially at play. Anyone in management will appreciate that message received does not always equal message sent even when everyone is doing their best and of good will.
On top of that, though, it would be simpler to have players give their NPCs orders as realistically possible and then just play everything out rather than constantly have to wait on someone to regain situational awareness following a diaper change in order for them to decide the henchman holds his action.
I have each player roll for his own character, henchman/men, and mercenaries (one roll for PC, one per henchmen, one per group of identical mercs/pets). I have the monsters roll for each unique named monster, and then for each group of identical monsters. If the number of monsters is large, I break it into groups of around equal size to the number of characters opposing them. For instance, if a party of eight encounters twenty goblins, I'd divide the goblins into three groups, of 7, 7, and 6 goblins respectively. I then count down from 10. If when I get to you, you don't know what you want to do, you hold.
I don't understand the argument that rolling for the group of identical monsters creates too much of a 'shock effect' as using group initiative (the usual alternative) means that every encounter is entirely shock, as all forces on one side go first.
I do think there is value in phased initiative for some groups. I used it for about 1/3 of the original Auran Empire campaign. However, the players found that the game was more fun with individual initiative.
I usually let each player roll once for his PC and the roll is also used for the henchmen using the individual initiative modifiers.
Then I roll once for all the monsters as a group.
The rest is just “who beats the monsters” can go first, then its my turn and then the remaining characters can act before the next round starts.
I've found that having the players roll individual Initiative each round keeps them engaged with the game. In the 3E and 5E games we played where Initiative was rolled only once at the beginning of a combat there would be a greater tendancy for the players' minds to get distracted by smartphones, etc.
That's pretty similar to the sequence in BECMI (and B/X), with the addition of "long movement." I'm not sure I'm clear on one thing, though: do you run that sequence twice in a round (i.e., once for Initiative winners, and then again for Initiative losers), or only once (with Initiative determining who moves first during "short movement," then who shoots first during "ranged," etc.)?
I think there's general agreement here that one d6 roll for every combatant is a bit much, particularly on the Judge's side of the screen. Like others, I also roll for monsters based on group, and sometimes I just make one d6 roll for all enemies if I'm feeling lazy. Similar to what my players do, I still adjust these based on individual modifiers (and have sometimes done so based on monsters' Surprise modifiers).
There is no initative roll at all, everything happens at the same time phase by phase. I decide the moves of the monsters in my head, then the players all move (or shoot) and then I do. If a situation calls for individual initative the players roll 1d10+Dex mod, on 7+ they go first on 4- they go last.
The effect apart from speeding the game up is that you can reliably get out of the way of spells being cast and an overwhelmning volley of ranged attacks, ranged attacks will reliably go before melee attacks and spellcasters will always have the risk of their spells being disrupted by ranged attacks. The melee all happening at once reinforces the feeling that it's one big clash and not a bunch of individuals who happen to fight near each other.