I'm one of the people who have had good luck with the Harbor Freight blades. I stocked up on them a couple of years ago when someone on QB noticed how cheap they were.
The only time one of the HF blades dulled quickly was when I was using a cheap little mat that came with a block of the month kit. It was the perfect size to take with me to my brother's pool and cut fussy-cut hexagons for my granddaughter's eye spy quilt. I realized it was the crappy mat that had dulled the blade. Now I have a small Olfa to bring with me.