I'm not commenting on how long the shutdown should be. However, for weeks we were in a state of limbo. Some states were shut down others weren't. It's likely that the marginal harm to the economy of a full shutdown (given that you're already mostly shutdown) is less than the marginal gain in fighting the disease.

What I'm saying is that you run the risk of damaging the economy without significantly altering the course of the disease. We need to be all in or all out. However, I suspect (just speculation) that if Trump declared today as national back to work day, we would actually just end up in that limbo state. Some would do it. Others wouldn't. The economy would still be damaged, meanwhile we wouldn't reduce the spread. People are staying home because they want to stay home in a lot of cases. Restaurants won't fill back up until people feel confident that they understand the risks. How likely am I to get the disease? How likely am I to die if I do get it? Is there a treatment available that significantly reduces my chances of dying? Until we can provide that information, the economy will continue to limp along, despite whatever policies politicians implement.