Inertia is not what you think it is
Inertia is technically speaking something that in physics is not what you commonly understand under the term. There is no mysterious "Inertia Force" that slows your actions on a setup. Inertia is not what makes you overshoot a print's endpoint.
Inertia is just the principle why you need to break (negative acceleration) before you reach the endpoint of travel and how much you need to and how fast you can step on the break (jerk).
Recap on Newtonian Motion Mechanics
Inertia is the fact that an item that is under movement and does not get acted upon just does nothing, as Newton's first law prescribes. That your applied force only takes effect on a body over time (the common thing understood under inertia) follows directly from the description of the 2nd Law of Newtonian Mechanics:
Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum
lineam rectam qua vis illa imprimitur.
The alteration of motion is ever proportional to the motive force impressed; and is
made in the direction of the right line in which that force is impressed.
$$F=\frac{d}{dt} (m\times v)$$
The Force onto a body is the change over time($\frac{d}{dt}$) of mass and velocity. In the classics physical case with constant mass, this becomes the much more well known formulation: $$F=m\times \frac{d}{dt} v=m\times\dot v=m\times a$$
Now, we have an item of known mass and a known initial velocity $v_0$. The speed of the item at any moment is thus $$v(t)=v_0-(\frac F m\times t)=v_0-(a\times t)$$
Momentum
Another thing that is often mingled into the therm inertia is actually the momentum of an item. It follows directly from the newton text: the force is proportional to the change of momentum. $$F=\frac{d}{dt}p=\frac{d}{dt}(m\times v)$$$$p=m\times v$$ Momentum can be best understood as an amount of "energy" (it's not, energy is $E_\text{kin}=m\times v^2$)
The principle of inertia is looked at in the slicer
Most slicers set a maximum acceleration for machines and jerk for machines. These values are decided based on the mass of the printhead: Maximum acceleration times the mass of the printhead is the maximum force. Jerk is the derivate of acceleration over time, so it flows into motion mechanics back as $F(t)=m\times j\times t$. So choosing the Jerk and Max-acceleration does include information about the mass of the printhead, without expressly stating it.
One could write the code in reverse and decide on a maximum allowable Force and include the mass of the printhead, resulting in automatically calculated settings for the maximum allowable 2nd and 3rd derivate of the position, acceleration and jerk.
Printer control boards just throttle
Likewise, printer control boards just throttle acceleration and jerk to a value in their firmware. They don't need to know the mass of the printhead if they put maximum values on both, and those account for the behavior wanted.
There is no accuracy to be gained from doing the calculation the other way around in the firmware: Even knowing the mass and some allowable force would not get you any way closer but spend quite some code on a function that is called for a few static values.
What is more influential, the acceleration and jerk settings are very heavily influenced by how your printhead is mounted, not just the mass of the printhead: Do you have a feather mounted on linear rails and moved with a screw? Or do we have a kilo chunk of lead mounted on a cross of 2 mm aluminium rod rails, pulled with a super soft rubber twist?
