Each major
conference (for instance in Theoretical Computer Science) requires 3 referees
per paper, and each major journal at least 2, so count the number of papers you
submit per year, normalized by number of authors and try to make your ratio
refereed /submitted above 3:1 (or 3:1 for conference submissions and 2:1 for
journal submissions).
If you
don’t do your share of work, it will be done by somebody else, of course,
meaning that you cannot complain if your conference submissions are briefly reviewed
by a PC member or if you receive an uninformative journal review clearly
written by an unexperienced referee.