I also agree. I just purchased a trial pack of 10 habor freight 45 mm blades last month. Some were dull to start with and others became dull very quickly.
I also found they did not fit my Olfa 45 mm rotary cutter well as the blades would spin around on the cutter axle rather than cutting.
I threw them all out and have gone back to the Olfa blades which can be purchased reasonably on sale.