A couple of years ago i exposed a couple of sheets of HP5+, while my meter was still set to the 25 iso needed for the P55n in used in the previous shoot. After considering the alternatives - the drop in contrast because of a reduced development or a dense negative - i decided on a 10% shorter development time and accept the dense negative. It took some effort to print them, but i was still able to get decent results, with very good shadow detail indeed.