Optimization: Central "update" system vs using Updates

I have searched on the internetz and found nothing about a system that would use a coroutine to update each frame, then in this coroutine, I’d run through a List of objects that contains all the Actions.

According to most people, using coroutine is more efficient than using Update, what if I use only one coroutine and iterate through a List each tick of the coroutine?

I’m not used to C#/Unity, let alone optimization, so I don’t know if it a good way to go.

A coroutine used like that is not more efficient that an Update because it would always run every frame. Further - having a single “Update” call does not tie together the lifetimes of your objects - so you could still be calling the action on an object that had been destroyed unless you also add that management to your central routine. In the end it would probably be better to just use Update or coroutines on the objects in question.