I've gotten to where when I need to see the DOF arrows, I hit the "Rapid Dimension" icon. Usually the sketch color change is enough, but there are occasions when the dof arrows help. When I tell new users this, they ask, "why aren't they always displayed, so I can see what needs to be constrained?".
I guess my question now, would this be a worthwhile topic to submit as an ER? Just a toggle for "always display sketch dof arrows", if the user wants them.