- this only applies to task-focused jobs; e.g. the service industry still needs people to work all the time customers might turn up
- studies may have picked companies/orgs that are likely to have the foresight and talent to try a new way of working; this may not scale well to general work
- how do companies that have customers that work 5 days a week work this out? Do you need two people working overlapping 4 out of 5 days so they cover all 5 days for every customer-facing role?
- if people can do 5 days' work in 4, can they also do 4 days' work in 3? What's special about 4 days? Will work scope down until it becomes true that it could be done in 3 days, just as 5 days' work seems to have scoped down to be doable in 4?