I've been running Mr. Tuffys since 1993. In all my MTB and clincher road tires.

For MTBs I keep 'em uncut. On road tires I can feel the lump in the overlap, so I install, ride a few miles, cut along the indent left by the overlap. Feather the cut edge with sandpaper or just on a rough sidewalk and reinstall.

I was tempted to keep riding on this tire with a Mr. Tuffy, but wimped out and got a new tire.

Oh, you can see a hunk of glass in there to the left. You need to inspect tires and dig those out from time to time as they'll eventually make it through the liner.