Bed Leveling Star

You're done with Bed Leveling Wizards, Heat-maps and Z-Probes? (but somehow your bed still isn't leveled nicely)

Alright then here is a more down-to-earth approach:

1. Print the smallest Leveling Star (100mm)---> the first one or two layers are enough while printing inspect the print:
- Where does it stick well to the bed? Where not?
- Is the first layer on some side more transparent/thinner?

===> The conclusions of course are:
- if the first la