The important thing is that these are *guidelines*, not rules. I think
the best practice is to include as many accidentals as you need to to
ensure that people can read it down quickly and easily, but not so many
that the chart gets cluttered up.
The only thing clear about the rules for accidentals is that in spite of
all the years of training and playing represented on this list, we're
still confused. When notating, use your experience as a guide, and put
the reading musician's needs first, ahead of slavish devotion to the
rules.
HP