I’ve never used slime and never had a flat. Go figure!
We have something call a goat head thorn in Colorado that can be on sidewalks and roads and cause flats anytime. I've hit patches of them a couple times and had from dozen two dozen in my tires such that even the flat prevention fluid like slime could not seal them all because too much got between the tube and tire. After 24 hours the holes would be sealed and I could then pump up the tire again.
If you live in wet climate there probably are no thorns like this. You can't ride more than a couple days in Colorado some times of the year with out getting a flat if you have thin tires nd no slop leak. Frustrates me that none of the tire companies are making like a 5-9mm thick tire is 27.5 and or 29er in a 2.4 - 2.8 width for urban commuter ebikes. The Moto X 27.5 is pretty thick but I still get punctures with them.