So each day, do you want G to pace your ad delivery so it shows all day (if you budget is less than recommended, it slows things to make them last the whole day) or do you want G to deliver your ads each day until the day's budget is gone and to have no regard if this happens by 10am each day kind of thing...
If you've got your budget set high enough, this setting hardly matters. If your budget is less than you spend each day, you need to decide if you want to pace spending each day or blow it out each day until it's gone.
If you're selling to businesses, don't pace. If you're selling to consumers, test each to figure out what works best.
