Brass instruments adhere to standard characteristics of physical laws. If we look at the series of partials (the notes that we can play without changing the valve pressed), they each represent a resonance mathematically related to the fundamental. Pedal C is the fundemental, low C at double the frequency, 2nd line G at 3x the fundamental frequency, 3rd space c at 4 times the fundamental...
In addition, based on the construction of the horn we have a "quality" of resonance (in physics called "Q") that determines how easy or hard it is to bend the note. If the Q is high, we have to exert a lot of energy to bend a note. If the Q is low, our chops have to provide the stability. Anyone that has been forced to use alternate fingerings on a Bach C trumpet, has firsthand experience about the Q of the 4th space E, Eb and 4th line D being too strong. The horn "wants" to play those notes very flat. Many trumpets also have a top of the staff G too high in pitch and a high C too low. That forces us to compensate with body tension - something that hurts our overall playing and sound.
Slotting is NOT the Q, at least not directly. Because we need to hear ourselves to tune, there is a perceived pitch and resonance that we call "slotting". The artisan building the trumpet must optimize the "targets" that we play, allowing moderate bending of pitch but a sense of security at the same time.
The resonance pattern of the trumpet also determines its tone in the various registers. Our brain reacts to a thinner sound of equal pitch with the sense that it actually is going sharp - we compensate by forcing the pitch lower - even although it is wrong. The opposite happens when the sound gets thicker - we force the pitch up.
My whole point is that "slotting" as a concept is flawed. We have to break down what affects pitch, tone and security. Players that "brag" about the "slotting" of their horns, generally play out of tune...
Now to confuse the rest, the "Q" of a trumpet is based more or less on bell flare shape (slotting is additionally affected by the mouthpiece, bracing and thickness/hardness of the bell). Standard horns are most efficient between low C and 2nd ledger line C above the staff. Above and below that, the Q goes down very quickly. Because Q is resonance, we have to work harder above the staff because the trumpet helps us less. A larger bell like on the higher Monette models, extends efficiency to lower notes. There is a cost of business however...