I ususally put the board on a flat surface and estimate the amount to
be removed for a flat surface. If it is 1/4" or more I start with
about 1/8" cut.

I find an initial deep cut easier to manage than multiple passes with a
shallow setting.

Technique is very important to avoid tapers.

I do not often use a jointer much anymore. I have a tablesaw jig that
lets me cut boards for a glueline fit with no jointing. So I usually
pass through table saw and the one pass to remove sawmarks on the
thickness planer.