How many ideas should be on each note card in the index-card method of note-taking?

Ead this sentence from the evolution of useful things.the underlined phrases indicateaaking waterproof sandpaper would allow wet sanding,which in turn would cut down on dust, and thus be a greatmprovementpassing of timea directional change of positiona cause-and-effect relationshipsequence of events.save and exitmark this and retur