I'm not sure about the default intervals, but minimum is 2 hours for free, and 15 minutes for pro/is. This can be adjusted in settings > update.
GG
I think the OP's question was misunderstood, by one of us ... those intervals you noted are for auto-update
checks to see if updates are available.
The updates themselves normally come out twice a day, more often if necessary. Typically I'll get one when I first go online late in the morning (Eastern Time, GMT-5) and another around mid-afternoon.
(Edit) Oh, and all def updates are for both versions, only the checks for them are more frequent in the Pro.