I go to the grocery store once per week unless I need something that I don't have at home.
I always buy at least 7 gallons of milk per week because we drink a lot of milk in this household so milk needs to be bought every week.
Milk usually doesn't keep past a few weeks at most and we drink it well before then as well.
Other stuff such as meats, vegetables etc we buy weekly as well.
Some canned goods I buy once per month by stocking up the first week of the month when we run low on canned goods.
But I'm always going to the grocery store at least once per week and I don't mind going to the grocery store often as it gets me out of the house.
And although I love my kids I hated taking them shopping with me when they were 2 and 3 years old as they wanted everything in the store and would cry and scream and have fits if they didn't get what they wanted.