I always get cautious when hearing such dogmatic statements. I would rather consider starting in the dark and doing erratic trial and error on all possible permutations of changes to different variables of a system a waste of time.
I prefer to have at least a basic understanding (or sometimes a hint or theory, e.g. 50% compression for the springs) of the variables and dependencies of a system and how they probably work. It is always good to derive a starting point and some hints/directions for experiments. This saves time in my opinion. And yes, the fine tuning and verification needs to be done by ear. The learnings should then be used to adapt the theory (maybe it’s then 75% compression or even different compression for different components or something totally different). This can at least help others for their systems.
Only repeating statements like "the only way is by hearing" renders this forum useless.
Very well said @hm9001. By design, comp springs "generally" should be in the 80% ~ compressed from free length to get within the low single digit freq.(<5Hz). Of course this gets one in the ballpark and will require experimenting etc.. but for someone to say
"All the calculations are a waste of time." 🤦♂️ ooy.