Conservation of a Sort

My lovely wife believes in conservation.  She waits until she has several errands in town before climbing into her Prius, thereby minimizing fuel use in the already miserly machine. She makes similar suggestions of me, making me aware of the waste of fuel and time involved in making multiple trips to our True Value Hardware store in order to complete a project.  My explanation that I'm not sure what I else I might need until I reach the next phase of said project, holds little sway in her efficiency quest.  All this is admirable, as are our composting, recycling, re-purposing, and reusing efforts.  But, there are conservation methods that I'm not exactly ... sure I buy into.  Let me explain,

She appears to be firmly entrenched in the belief that conservation includes things in daily use, e.g. hinges and switches.  She will switch on a light when entering a room then leave without switching it off - her rationale "I'm going back in there, soon."  Soon, may be a minute,  an hour, or more.  Similarly, she will open a cabinet to extract something and leave it open with the thought that she might need something else from there, soon. Finally there's the stove - maybe this one's a bit different conservation-wise, you be the judge.  Often she will turn the burner on (electric stove i.e. heats up very fast) and then search for the pot or pan she needs.

Do these miscellaneous foibles negate our conservation efforts in other areas?  I have no answer to that.