What if the studies that say extra time in the office is often wasted are true? Should people give up some comp to not sit in a seat?
The studies may be wrong, or maybe you pencil it out and it just doesn't model out correctly, but if you lock in the pay on the basis of the assumption that the total productivity would be less, it's sort of favors one side of interpretation. And if you're truly trying use a four day week to attract high-end talent, reduced per hour pay somewhat dilutes the attraction of the benefit.
Finally, some consulting gigs are billed per hour anyway, so the model might end up that total comp is somewhat reduced vs a full 40/hr week. Or it might end up the same pay for four days - it really depends on the business model.
