I skimmed through the Spheres' presentation to try to give a good answer with examples.
For example, in the Level 3 of Forces you have this part :
"attach elemental force to material forms – making them fly, pinning
them to the ground, and having other, similar effects (generally with
Life or Matter 3)"
P.516.
This means that globally to realize this effect, in general you would need Life or Matter 3 but for "less complex" lifeforms or materials, the Level 2 could be enough and in the inverse for strange lifeforms or matters, maybe a level 4 or 5 could be needed.
In the same vein, Time, Page 523 :
Now the mage learns to withdraw herself from the normal flow of time,
hold Effects until they get triggered by events, or – by adding in
Correspondence, Forces, Life, Matter, and/ or Spirit – capture other
beings or phenomena in bubbles of time.
The levels of Sphere for Correspondance and Whatever are not specified but should be in adequation with the complexity of the affected phenomena and the level of Sphere you need to affect them.
Ergo, you will not be able to freeze a Level 4 Correspondance Effect if you yourself do not understand the Correspondance Sphere as this level.
The Mind Sphere as a support is the same. Is the intensity of the support you want to give level 3 ? Then the needed level is 3. This means you can flexibly change the intensity of the support Sphere depending on what you want or, more often than not, what you do.
Or at least, that is how I understood and played it.
