How often do you feed your dog?

My family and my husband's family have different views on feeding their dogs. My husband's family leaves food out for their dogs all day. My family has always only fed their dogs once a day (twice a day as puppies). My family follows the instructions on the back of our dog food bag. My dad is also a police officer who has K-9 dogs and that's the diet the trainers have the dogs on when he first gets them. So we've always done the same thing as they have and our dogs have been healthy weight and lived longer than their life expectancy. My sister feeds her dog all day (she's a little dog and takes about 5 minutes to eat one bite, so she leaves it out). I'm just curious as to what you do. Our families have been arguing on how my husband and I feed our dogs because no matter what we do, it's not right to one side of our families. What do you do?