I routinely cover the ASI when I fly with students as it is a great way to make the point that attitude + power really does equal performance. This is especially effective on final as students are continually amazed at how well they can judge the airspeed just by assesing the attitude and noting the power setting.
As for checking the pitot heat before a day VFR flight..... I would suggest that care should be taken to ensure that one has not fallen into the trap of treating every check action as having an equal importance to safe flight, which is absolutely not the case, and making sure there is full understanding on "why" you are doing something not just on "what" you are doing.