potatoes in containers

Hoping for some input--for years I have been growing potatoes in various containers with pretty fair harvests. I always grow Yukon Gold, but in the last 2 years have added small ones, like Pinto Rose & Russian Banana. I always read that I should start the tubers in about 6" of soil in the container, and add more soil or mulch as the tops get about 6" above the soil. But I never have any potatoes form up above the original tuber- so why not just plant a little deeper? All the babies are below the parent. Any advice will be welcomed ! Thanks- Jo in the PNW where we didn't really have winter !