Been there, did that. Should have printed out the t-shirt.
I had at one time hand-written notes for redoing many of the games monster entries to bring everything up to the MM2 standard and my own house rules. This included big updates to two things correcting XP entries and correcting/improving how AC was recorded in the MM. I had started using the "To Weapon vs. AC" tables in the Unearthed Arcana (with some minor tweaks, like making axes a bit heavier hitting just to bring some variety) and the problem was I wanted to extend this to all monsters. The entries and rules seemed to imply that monsters had armor equivalent to humanoid armor, but with the same modifiers for dexterity or magic or whatever. So I set about separating the AC of all monsters into two numbers, actual "Armor Class" (like '5' equivalent to chainmail) and the monsters "Armor Bonus" the adjustment to the AC up or down. This would be written as like 5(+2) or 2(-2) or whatever. AC 5(+2) differed from AC 3 in that you used a different column in the "Weapon vs. AC" table. I soon noticed that functionally this was giving me Dexterity values, which I also adopted because I wanted more monsters with bonuses to initiative owing to the fact that if the party on average tended to go first the fight was a rout and generally over before the monster could really react.
I handled all this extra complexity by making "to hit" tables for each player character for each weapon they commonly used. The result of this was my game actually sped up, because they could just report the number they rolled unmodified and the math was built into the table - no more losing 3-5 seconds each attack adding the fiddly bits.
You win!
