  In effective models of loop quantum gravity, the onset of quantum effects is
controlled by a so-called polymerisation scale. It is sometimes necessary to
make this scale phase space dependent in order to obtain sensible physics. A
particularly interesting choice recently used to study quantum corrected black
hole spacetimes takes the generator of time translations itself to set the
scale. We review this idea, point out errors in recent treatments, and show how
to fix them in principle.
