4 - 5 times a week does it for me...............because it has to.
I was out of gym and on junk diet for a while (4 months) as i purchased a house on which i worked like crazy to get it back in shape (5 months of carpentry, plumbing and electricity wiring throughout the whole fuken thing)
So i let myself go, now i got love handles and somewhat of a gut (my beautiful abs, where are they??????) and started out slowly, but upped it to 5 times a week at 27 - 30 min a session.
Loosing fat and building back the stamina and repairing lungs on the way from all that demolition dust and cigarette smoke......