The identical pork butts may be a good case to clarify the concept.
Twin#1 is cooked at 325°
Twin#2 is cooked at 225°
Let's also assume the appliance (smoker/grill) are also identical. Twin#1 preheated to 325° and Twin#2 to 225°. Also ignoring the fact that there will be more air convection at 325°.
I am at work and doing this by memory. So the numbers may not be correct.
Air carries 0.005 BTU of heat per degree F per cubic foot. At 325° there will be more BTUs to heat up the surface to a higher temperature than 225°, still the moisture in both #1 & #2 will prevent the heat to go to 212F.
The surface temperatures, if measured by an IR thermometer, the 325° twin#1 will be higher than Twin#2. However, based on the same thermal conductivity constant for both #1 and #2, the higher heat and the lower heat will travel at the exact same speed into the center of the meat.
Soon, most of the moisture will be dried up by the heat for both #1 and #2 and the surface temperature for both will get to be close to 212F. At this point, and again because of conductivity is a constant property, the 212F heat for both #1 and #2 will travel at the same speed into the center of the meat.
High & fast, heat will get the center hot faster but not much. It will give the exterior the kind of mouth feel that is desired, but it will dry out the exterior faster. For thick pieces of meat there is also a concern that the center may not be cooked.
Low & slow, meat will alway be cooked. It is a method to control meat texture a different way for different kinds of cuts.