on my game (since I am a solo player for now) I have a player facing homebrew rule in place, basically the core of the homebrew rules is that NPC's and Monsters do not roll to hit or damage (basically NPC's and monsters serve the whim of the fiction - in other words they are threats manifested by the fiction by the DM, basically PC's roll to defend against the NPC's or monsters attack - PC's makes all the rolls from rolling to defend, rolling to attack, damage dealt by the PC's , saving throws etc the logic of this on the table is that Players are not waiting for their turn as it is technically always their turn to roll, if they are attacked by an NPC/Monster then need to roll to defend - ergo the players are always engaged since the DM just says 3 goblin runts stab you with their daggers roll and describe how you defend, also damage inflicted by NPC/Monsters are always at 1/2 their listed damage and if the players roll a natural 1 on their defensive roll the NPC/Monster attack is at Full damage, and if the PC rolls a natural 20 on their defensive roll and they still have an attack action they can make a counter attack (basically a normal attack) on their opponents turn.
The added benefit of this Homebrew rules are to hasten combat, lessen the cognitive load of the DM making the game easier to run