- The impact is dampened because most hard roles aren't going to work 80% time. Sales, customer support, executives, and the important engineers will just work 5 days a week anyway, so you end up with like 4% less actual work being done, so it takes a while for this impact to be clear.

- There are other strategic differences which can easily swing a company +/- 10%, so looking at just two examples might not give clear guidance on the overall effect.

- You would be shocked how many mental gymnastics one can do. Never underestimate how far they can go.