I only put enough out that they will consume in a day. I imagine it probably doesn't taste as good sitting out long, kinda like crackers and cereal if they are left out more then a day, they taste stale.
Ours gets a portion that they finish in a few hours. The only time it would set out longer is when we fill the bowl for weekend show trips. I'm sure its all gone by sometimes on Saturday. They have plenty of water and many times I've come home with a few crunches left in the bottom
I would only put out enough for the day. I give Bijou and Mika between 1/3 and 1/2 cup of Orijen per day. They get wet food morniing and night. Mika actually prefers dry and Bijou wet but they both eat both wet and dry. Bijou is usually asking for his wet food when we get home from work whereas Mika will go first to the dry and then the wet.
By the time I get home from work in the evening, both dry and wet food bowls are empty.