If a scientist has x number of affiliations, and he or she strikes some deal with these x to be part of the coauthor list (in their peer reviewed publications) then it is not farfetched to reach x * y publications per year (assuming absence of anything unethical), where y is the avg publication rate of x.
However, there are two aspects:
1. whether one is actually happy with being a "dummy" author in someone else's efforts.
2. Since the scientific community itself has kept all these metrics to evaluate the productivity of the 21st century scientists, would the peer pressure twist the morale of a scientist to select option 1.
Because, as far as I learned, even if one (as PI) have a very active and big research group, it's not so easy go beyond 20 to 30 papers per year as the intermediate and/last author, may be 1 at best as first author.