To be clear, I'd still want us to be able to pick two of these affinities for our characters to blend them in a primary and secondary way. Even as you've said before, two people with the same affinities can have vastly different magic. Let's make an example of Air and Water as a pair:

The first mage calls the storm, cracking the sky down onto their foe with torrential rain, ear splitting thunder, and the devastating stroke of lightning from on high.

The second skates across the battlefield like a dancer, propelling themselves up, down and around with flight. They weave razor sharp slivers of ice into blades that tear their enemies asunder, or snap freeze those unfortunate enough to survive the first assault.

Edit (sorry km kinda scatter brained and afterthoughts are common for me haha): Now this definitely seems like the first is just hydromancy and electromancy, while the second is aeromancy and cryomancy, which is true. But with the affinities as I described, the first would still easily be able to fly or use wind magic as per the Air affinity (and ice with the Water affinity), and the second would be able to transform those icecles into water and attack with them, or just use electricity if they wanted. It might not be optimal for them these other ways, maybe they are more drawn to the depictions I gave them, but my goal is that the option is there.

For me personally, electricity has always been very closely associated with the element of air, and a lot of the other consolidations I suggested follow suit.