Derby works for me. I get 3 shaves out of them.
Derby's are so inconsistent with their quality control, most likely due to worn out manufacturing equipment.
Top quality blade manufactures replace equipment on a very regular schedule, as tooling wears with use.
Derby has most likely not performed a lot of required upgrades lately, resulting in bad batches of blades being produced.
Because of the inconsistent quality getting shipped, it's possible all of their QC employees have been replaced with a rubber stamper.
I have no reason to try their blades again, once was enough.
I'm just now finishing up a carton of Derbys that I bought in 2009. Been using them in a Star de for about a year and a half straight. I don't know about the newer ones but my carton was good. Doubt I will replace them though, as I like Lord Platinums better.
Don't know if they still make them or not, but Bluebirds are a similar blade to the Derby, but at least in my opinion they are sharper. Some people find no difference between the two and think they are the same blade with different labeling, but I found the Bluebirds to be sharper. Anyone who liked the smoothness of the Derby but found them dull might try a sample of Bluebirds if they are still made.