Every animal is different, as is their environment. Willow is (mostly) very well behaved when caged. I will not leave her out when I (or a family member) is not around for both her safety and my house's.
That said, I work 12 hour shifts, so when I'm working, she is in her cage anywhere from 4-15 hours straight at times. Keys are fresh food/water, and toys that the bird loves. In Willows case, 90% of that is colored wood she can destroy, along with her plastic toys, string/yarn/rope toys, and even metal chains from time to time.
I also tend to leave the lights on, window shades open, (her cage is in the window for sunlight and visual entertainment) and either the TV or radio on for her.
Days I'm off, she's out most, if not all day, usually downstairs on her perch/cage. (She has both side-by-side in the living room.) If I am gone for short periods of time I'll leave her downstairs in the cage with the TV on. Any time I'll be gone an hour or more it's upstairs in her big cage (which is the size of a fridge.)
My work schedule is pretty much up 6:30-7am, Willow is out until I leave at 8, and then it's either she stays out if someone is home, or it's upstairs until someone is home. (10pm for me.)
Days off, it's out all day, unless I go somewhere. I'll pop her into the cage if I'm outside in the garage or mowing. If it's nice/warm out she'll come outside with me on the porch in her "travel" cage.
A lot of people will tell you to keep a steady routine, and I too would recommend this if it is possible. My schedule however, it was not. I got lucky with a very well behaved bird that does not scream very often, and 1 brother that lives with me who she loves.
Every situation/bird is different. Take your time, learn each other and work on bonding and gaining his trust. Keep lots of toys, and change them regularly. Watch for dangerous ones. Be careful not to over-stimulate (as it usually results in biting) and make sure the bird learns to self-entertain.
Good luck!