Question Is writing inside a GhostInputSystemGroup system strictly necessary?

Hey Richay,
Apologies for the delay on this. IIRC the GhostInputSystemGroup only exists as a convenience for users. From the docs: "it runs before the CommandSendSystemGroup in order to remove any latency in betwen the input gathering and the command submission. All the your systems that translate user input (ex: using the UnityEngine.Input into ICommandData command data must should update in this group." Emphasis mine.

Therefore, as long as you are able to write before the CommandSendSystemGroup, you're not introducing any latency, and it should be just fine.

 

I would like to correct @NikiWalker answer a bit here because it his marginally incorrect.
The idea behind the GhostInputSystemGroup is to indeed to limit latency. And all she said in regard the handling is exact, if you are using ICommandData directly.

But with IInputComponentData things are a little different. We auto-generate system that translate the input into the underlying ICommandData buffer. And these systems runs last (at the moment) inside the GhostInputSystemGroup.
So it this case it is mandatory to update your input BEFORE or inside into the GhostInputSystemGroup