Twice a day seems to make the most sense (for adult dogs) so that's what I've stuck with.

With GSDs you really have to watch out for bloat so you don't want to feed less than twice per day.

With any dog though you can majorly reduce begging by feeding twice a day. It's quite nice with less begging.

I skip meals one day per week (aprox. 25 hours) to let their bodies heal. (There is scientific evidence proving that they benefit from fasting. Has something to do with enzymes that are only produced when their digestive system is relaxing.)

It takes raw food six hours to go through their digestive systems and 12 hours for kibble to. (Varies by individual, breed, and current health.)