how long a dog can be left alone varies on the brred of dog, the dog's emotional state and his or her energy levels.
Young dogs and puppies should not be left alone all day. It is not good for the dog and can lead to behavior problems later in life.
Some adult dogs are left up to 8 hours a day while the owners are out at work, but this is not recommended, as the dog needs toilet breaks and, if it is small dog, may require a feed during that time.
Schnoodles in particular are people- friendly dogs who enjoy the company of humans. For them to be alone all day would be harder than say for a breed which is less focussed on humans.
It is interesting to note that many rescue organizations will not release dogs to homes where the dog will be alone for more than 4 hours during the day.
If you are seriously thinking of getting Schnoodle and youi are out at work all day, can you arrange for a dog walker or neighbour to come in during the day to exercise your dog or spend a half hour with him or her?