Should principals stop visiting classrooms?

"Just pretend I am not here....."

Should principals stop visiting classrooms?:

What?!?! Principals are supposed to be instructional leaders, how could they do that with out visiting classrooms?  The post by Daniel Willingham offers some insight into a study conducted by Jason Grissom, Susanna Loeb, and Ben Master on the issue of instructional leadership.
As Mr. Willingham points out, the method of the study is what makes it interesting.

 He states: "Instead of simply asking principals how important is instructional leadership to you or having them complete time diaries, researchers actually followed 100 principals around for a full school day, recording what they did. "

A conclusion that the researchers came to was:

Time spent coaching teachers--especially in math--was associated with better student outcomes. So was time spent evaluating teachers and curriculum. But informal classroom walkthroughs--the most common activity--were negatively associated with student achievement. This was especially true in high schools. 

As a hopeful future principal, this conclusion is interesting.... but not surprising to me!! I view the principal as an instructional leader who collaborates with the teachers to improve their teaching.  When this relationship and understanding is clarified between the principal and teacher, the classroom visits are viewed as a positive, supportive experience; not a negative evaluative experience.

So, should principals stop visiting classrooms? No, they need to.  They need to know what is happening in the classrooms of their school.  But the principal needs to cultivate a relationship with the teachers so they understand the visits are to support and help them become better teachers.

All you principals and administrators out there, what do you think?