Studies show birds can live a lot longer and healthier if you let them get some "workout" every day. The same goes for almost all pets species.
I let my budgies out of their cage almost every day for an hour or two, but it is usually limited to a single room. Keep in mind that there can be a lot of hazards for the pet birds even inside a common house or an apartment.
A few examples:
The toilet, the electric outlet and wires, common household chemicals including soap, shampoo, and cleaning products, etc.
Aside potential hazards for your precious pet birds, they can also cause a lot of trouble by pooping everywhere or chew through the things you might not want to have an extra hole in them.
