puncture preventative gunge
I first started using puncture preventative gunge back in the early 70's I think (whenever OKO first started becoming available anyway), after I had a pretty nasty front tyre blowout at high speed. Managed to keep the bike upright and not hit anything, but that's not saying a lot.
Never had a problem with it, early on with tubed tyres, later and currently with tubeless radials. Not using OKO at the moment (dunno what it is, same sort of gunge, but OKO isn't available round here), but I wouldn't even begin to think of not using an equivalent.
One front tyre, when replaced, was found to have 17 punctures in it, and I'd never noticed more than about 1psi to top up when checking pressures.
Safest stuff you can shove on a bike, apart from the rider. I'm out on the bike all year round in all sorts of weathers, often miles from anywhere, and the stuff is invaluable.
Government should be subsidising the stuff and not pissing around wasting people's money with ridiculously stupid EU imposed driving tests imho. It'd make more sense to me anyway.