The one thing I do that aids in things is to not be completely dogmatic about the game mechanics when it comes to combat, and instead be more than willing to do narrative depending on what players/monsters wish to do.
Case in point, retreating. If the players want to retreat the game mechanics are set up such that the player moves, the monster moves and become adjacent, the player moves again and the monster gets an opportunity attack, the monster then move adjacent again, etc. etc. etc. And in "theory" the PC gets killed and can never get away if you stay strictly with game mechanic combat above all else.
Which is why I don't. If a PC runs off to retreat, I might have a monster move once to try and engage... but often I'll just zoom out narratively and say the monster watches the retreating PC, maybe fires a ranged attack at them if they have one, but otherwise the PC can just get away. And I can make that decision just as the DM for what makes sense to the narrative of the fight we are in, and thus never have to create these complex "house rule" systems for retreating in order to let PCs get away within the context of the game mechanics.
The game mechanics for combat are fine and all... but they aren't so great that I care to keep every single fight within their ruleset. At some point just waving my hand and saying "what makes story sense here?" trumps any need for an enslavement to the miniature combat rules.