The D300 has autofocus. It also has the ability to adjust AF for front of back focus. What Lens Align does is give you a basis for making an adjustment. This is the kind of prcision adjustment that should only be done with very accurate and repeatable testing. to do otherwise will make things worse.
I’m with Eric on this one (response #6). To coin a colloquial phrase, “if it ain’t broke, don’t fix it.”
Often, focus sharpness issues are “user generated”—deriving from things like shallow depth of field, wrong focus point and/or focus method, camera support/stability, subject movement, improper shutter speed choice, etc.
That’s not to say that lens alignment (front and back-focus) issues can’t occur—because they do. Just be darn sure that this is the case before messing with the alignment, rather than doing it just for the sake of trying to tweak a good working lens to technical perfection. Just my .02