Hi sandi_k,
You’re certainly right about that. Unless you have a great deal of knowledge and experience with different types of mattress materials and specs and different layering combinations and how they combine together and can translate them into your own “real life” experience that can be unique to you (which would only be a very small percentage of people) … using individual “comfort specs” such as layer thicknesses or ILD numbers or compression modulus or other complex combinations of information or specifications to try and predict how a mattress will feel or perform for you or how it will compare to another mattress will never be as accurate as your own actual testing and/or personal experience.
Every layer and component in a mattress (including the cover) will have an effect on the feel and performance of every other layer and component above and below it and specs such as ILD are only one of several variables or “specs” that will determine how soft or firm an individual layer or a mattress “as a whole” will feel to different people (see post #4 here). In addition to this the ILD of different materials or different types and blends of latex also aren’t always directly comparable to each other (see post #6 here) so using the ILD or other specifications of a particular layer or combination of layers as a reliable indication of how any mattress will “feel” or how firm it will feel to you compared to another mattress with a different combination of layers can be more misleading than helpful.
While knowing the specs that can affect the quality and durability of the layers and components in a mattress is always important … when you try and choose specific layers or components based on complex combinations of “comfort” specs that you may not fully understand (or that may not be available in the first place) then the most common outcome can often be “information overload” and “paralysis by analysis”. Even the best mattress designers in the industry are often surprised at what a mattress they design “should have felt like” when they design it and what it “actually feels like” when they test out their new design.
Phoenix