I used Mr Tuffy once – and they gave me a flat about 3 hours into a 4 hour ride. The end of the liner chafed against the tube and wore a hole in the tube. I couldn’t figure out why I would be loosing air when I was riding, but then I did the autopsy when I got home.

Slime in tubes didn’t help me at all with pinch flats. Has given me enough air to get home safely, then I find the problem the next morning.

I now go tubeless with latex (which does dry out and require maintenance unlike old school slime). Seems to work great as long as I don’t rip a hole in the side of the tire at least (hasn’t been a problem yet). Bonus - totally eliminates pinch flats.