During my first stop at the well known Mertz Apothecary here in Chicago the gentleman behind the counter warned me that he has experienced a bad blade in every pack of Derby's he has used. My first experience with the blades wasn't the greatest (one weeper and a bit of razor burn). Have any of you experienced a similar experience with bad blades in each pack or do I just need to keep working on the well known mantra of "take it slow, less pressure"?