glider pilot...not the end all
energy management in any form is a good practice for a power off approach and landing.
I like bubber's posts in general, but disagree on this one. Gliding is not the end all to a power off approach in an airliner.
AS most of you know, most descents are at idle thrust...while not the same as power off, it can approximate gliding. Now, we don't fly power off or at idle to a landing (being unspooled is a no no for a go around), we always gauge our energy in one form or another.
After all, sully hadn't taken up the A320 and practiced gliding it...he flew gliders. I advise every pilot to reread "stick and rudder'' and how to gauge the approach.