Perhaps your blades are dulling faster because of the mat you are using. I've particularly noticed this with the gray Fiskars mats and other like them. For over 30+ years I have used on Olfa mats, the original quilt cutting mat which came to use from the engineering field. They are truly self healing where many others are not.
Also it's possible you use off brand blades; again where Olfas are best (and others like them).
I mark my blades along the very edge with the date I install them; helps to keep the time to change in mind each time I open the blade.
Jan in VA