For a big company at least, I feel that this is an ideal world solution rather than a real world one. The amount of hours tasks take are going to be really hard

For a big company at least, I feel that this is an ideal world solution rather than a real world one. The amount of hours tasks take are going to be really hard to estimate, meaning that your work hours will on part depend on the luck of tasks allocated. Also you will have plenty of people out to game this by setting low expectations of what can be achieved in the week and making those in less hours.