I am just trying to deeply understand relations between those parameters. I am not a noobie, but just trying to be more smart with a printer, instead of changing parameters randomly to see effects on the print.
So Let's Assume Bed is leveled perfectly and all Motor steps are calibrated correctly (X,Y,Z,E)
I do understand some of the correlations e.g.:
When Flow is too low, on first layer you have to lower Z-Offset to get nice squish, but next layer will be under extruded, because Z-Offset does not apply on any layer except 1st.
When your flow is too high, you have to bring Z-Offset higher, to get first layer perfect, but then next layers will be over extruded and looks squished too much.
Now, I have calibrated flow, with method of printing shallow cube with 2 walls (perimeters). I've set all line widths to be 0.4 (like my nozzle), so on the measurements I expect wall to be 0.8 (2x0.4), some tutorials says I should aim for 0.82, but for now I left it at 0.8 which was pretty much spot on.
Leaving line width's set to 0.4 for all lines and layers, and line height to 0.2 on all layers, I started printing, on the fly I adjusted Z-Offset to get that first layer right. But on every other layer, I had too much squish (over extrusion). And that does not fit the things I though I understand. Because now if I lower flow, flow calibration will come wrong. I also know that by default in most slicers, layer height and line width are not set to same values for all layers.
Of Course I could just fiddle around, keep changing those settings and probably I would finally get what I want, but I want to understand what to change and why, so rather than telling me what I am doing wrong, I would like to know how it should work, I am guessing there is How it should work in ideal world, and how it works with budget printers. But I really really want to understand that part of the printing, and maybe there is other complications I am missing in here.