From my experience it helps only with collision and physics constraints, anything you calculate yourself in Tick() gets very little benefit from sub-stepping. The whole point is to do calculations of your forces INSIDE of each sub-step.
To see if your setup benefits from sub-stepping lower your fps artificially and see if it still behaves normally. Something like dampener in suspension calculation, can heavily dependent on delta time and when you tweak it to work nicely at 60 fps don’t be surprised if you get completely different behavior at 30 fps. By doing calculation inside of the sub-step you guarantee that your physics update has more or less the same frequency, regardless of how many FPS you get from rendering.