Maxperson
Morkus from Orkus
The main issue I have is that it doesn't really make the combat feel more real, it's just unreal in a different way. If you think about it, drawing an arrow, nocking the arrow, drawing back, aiming and firing is not faster(let alone twice as fast) as swinging or stabbing with a sword. A crossbow is going to be slower than a short bow. A greatsword is going to be slower than a dagger. The dagger will be faster than the short bow.Some time after I first tried DMing 5th edition, I ran into a video by Matt Colville in his Running the Game series on YouTube. In it he mentioned a really cool alternative to initiative that one of the creators of 5E came up with:
D4 for ranged. D8 for melee. D12 for spellcasting. +D6 to move and/or do something. The lower rolls go first. This process occurs at the beginning of each round.
There are a couple of things that this accomplishes extremely well. The more actions you make, the longer you will need to perform them. Also some actions are more complicated and take more time to perform.
Not only is this more immersive when players think about how long it will take them to do what they want to do, but it actively encourages players to have fun strategizing with each other during many rounds. It also adds a very welcome layer to the strategy because now players can actually try to get an earlier initiative on a given turn, and they have to think about the cost/benefit ratio for the things that they do. E.g. "how can I heal Rumlar, and do it quick?"
So IMO this alternative is not only mechanically superior but it is more immersive. It makes combat feel real.
If you want to make combat feel real and immersive. Roll every round with a d20 or if that's too swingy, a d12 and then add weapon and spell speed factors to it. You can add that d6 for movement if you like.