I learned long ago ... take 5 .... 10 in a pinch ... any more is risking a ticket.
And watch the road like an infantryman. If you see someplace that is a good ambush site, sure enough there is a highwayman ... oops ... a highway patrol officer, waiting to radar you and make off with revenue.
Oregon has radar, too ~ I'm retired and in no hurry and usually drive very close (except on the twisty back roads on my bike and there I keep it under 130mph) to the speed limit.
My wife uses the cruise control in town when driving her SUV; it's funny to see someone using the cruise control at 30mph. :):):)