If sharing a mattress, the TYPE of springs matter a lot in relation to comfort. With bonnell springs, all the springs are linked, so when someone moves on one side of the mattress the person on the other side is moved too. If someone is sitting on the mattress they can be launched off the bed by another person plonking down on the other side of the mattress - just like with the old bladder-less waterbeds.
With pocket springs, the springs are individually packaged inside the mattress and no energy transference occurs. Thus each person gets a much more comfortable night’s rest. Pocket springs also allow for more comfort in terms on better moulding to each person’s shape, no matter what position they sleep in. (Pocket spring mattresses do cost more though, but it’s worth it in my opinion.)
Only then does the number of springs come into play. The more springs, the firmer the mattress. Personally, I like a very firm mattress, so for me, lots of springs are good Other people like softer mattresses with less springs.
I have lain on a ‘zoned’ bed where they supposedly have different springing top, middle, and bottom “to accommodate the shape of your body”. Personally, I think it was a sales gimmick as it didn’t feel as comfortable as a good pocket spring mattress.