I was finding a couple of years ago that my blades were not lasting and using the sharpner wasn't helping some of them A quilter on another board suggested I make scrappy quilted cases for them and get into the habit of sliding them into the open end of the case when not cutting.This seems to have helped with the length of time they cut well!

When mine starts missing places regularly, I change blades.

I change it when it's causing me too much stress to cut. lol

I was just having the same problems, and thought the blade sure wore out fast. turned my blade around, not any difference. Well, went to fabric store to pick up a few things and decided to get one of the June TAYLOR cut and press mats because it was bigger than the old one I had at home. That mat is a lot harder it seems, and the rotery cutter is working like new. I also think I was pressing too hard on the softer mat, and I believe that was what made some of my strips not quite the same size., the fabric was actually going into the mat.

Try turning the blade around and adding a drop of oil on it. Just make sure that it's only a small drop and you let it set for awhile then run it though scrap material.

Also, clean your mat well. I have a very old Dritz (10 years) and as long as I keep it clean (I don't use the lines on the mat). I wipe it down with the dishcloth when I do dishes......

You might have put the cutter together wrong. It shouldn't wobble. On my Olfa - there is a black washer thingy - if it is backwards then mine is not tight.

check to see if you put the nut back on the right way. there should not be play in the blade. the older white colored mats are terrible on blades. if your blade is sharp, you really should not have to press hard. remember how a new blade cuts ?? It should be that way all the time.
I find it easier to change often than re-cut threads. a little drop of oil under the blade when you change is good too. be sure to cut through some scraps in case of oily residue.
but don't wipe ! good way to get cut.

You may have nicked the blade on your ruler. Happens a lot to beginners.,
As for having to "reswipe" and then being off the line, only cut the area that missed, don't go over the whole cut.
And, always keep a spare blade handy.

My sister told me to keep my hand over the blade not behind it. This has helped me quite a bit. It's much easier to keep an even pressure and since my hands can be weak at times I need all the help I can get. I find that very often when a somewhat new blade is not getting through the layers it's because I have let my hand drop back to far. I hope this makes any kind of sense.