There was a case when constant propagation do not work well. And the case is pretty complex. The case is mixed with Undo/Redo code. So may be a problem in Undo/Redo, Extrude itself or other problem. So from any moment may be a solution I would hope to find, but for certain is not obvious.
Also, today was make that parametric modeling will create undo/redo points. This makes that there the defined guard will be able to have both visual impacting changes or non visual. The non visual changes will only create an Undo/Redo point. A good thing also is that there is a minimalist code to make a undo/redo to happen by adding two lines in code.