This thread should be very helpful to answer your questions. In general, it boils down to how “bumby” your bed is. So, not the values itself, but how they are distributed across your bed matters. A gradient, tilt or curve can be compensated by the auto leveling, but bumps, dents, wobbles are an issue. In my case (Kickstarter A350) I realized that not the bed frame is the culprit (which it also can be), but the heated bed PCB actually is uneven like hell.
Solutions are either to work with shimming to try and force everything into shape, or work with denser auto-levelling patterns. With my old platform and bed I needed to go for 11x11 mesh to get somewhat uniform first layers on large prints, with the newer platform but still old bed the densest pattern of the dual extruder (5x5? don’t remember right now…) seems to be just good enough, but I did not run very large prints with that setup yet.