Hi beanbag,
I caution people on a regular basis about using comfort layers that may be too thick or soft for them yes.
There are some links to some generic guidelines in mattress firmness/comfort levels in post #2 here but there are too many unknowns, variables, and individual preferences to use generic guidelines, specs, or “theory at a distance” as a way to choose an optimal mattress for any specific person. People and bodies can be very different from each other 
Phoenix