Our old dog ate once a day after he was an adult, and never had any noticable issues with it.
I feed Meg twice a day, mostly because I can't imagine only eating once a day myself
. I do tend to make her morning meal bigger than her evening meal so she isn't going to bed with a very full tummy (I feed pretty late in the evening). Maybe 70% of her food in the morning and 30% at night.