I wouldn't expect that every food product be cooked in every pan. Of course not. But at different temperatures, sure. We know not to eat chicken cooked to below 165 degrees, beef below 140, etc. With mods, I'd agree that each different chip be tested at many different voltages. So not every mod, since many mods use the same chipset.
I would agree that testing be done at, say, 2 volt intervals. When the release of toxic chemicals/aerosols is too high for user safety, you would fine-tune the settings to look at every 0.X volts. It will be a long process to look at these measurements across a wide range of resistances, but if a specific voltage is discovered to produce unfavorable results, that will help guide the industry in how powerful chips should be allowed to get.
This also means that a LD50 be tested for inhalation of those chemicals, as well as a useful confidence interval and p-values.
I understand that all the mod does is supply the power. And in the case of mech mods, that all comes down to the battery and resistance. But with regulated mods, I wouldn't be opposed to knowing that the power supplied is accurately displayed on the screen. My Invader mini varies so much between hits, that I don't use it anymore. With the same tank on it, set at 12watts, I've seen it read anywhere between 3.5-4.2 volts. Testing chips and mods will only help to ensure that the power you are expecting is the power being delivered.
As for what should be regulated as tobacco products... I think e-liquid containing nicotine should be. That's not even a question any of us should be asking ourselves. Tobacco leaves are used to produce the nicotine. But 0nic juice and the mods themselves should not be regulted as such. But in order to test nicotine juice, it should be done scientifically, which involves testing the product that supplies the power to create the vapor