Yeah. You need to nut out why they work. And then nut out how likley it is that the situation will present itself that will make that technique work. For flying kicks it is almost purely street. So it is hard to recreate in the gym.
In training you are probably not going to get many situations where you may be running. Gyms are to small.
But if running is part of your self defence. Running attacks probably should exist as well.
So we have this kind of sort of mix between hypothetical. Ancecdotal and empirical. Not to mention overcoming dogma and peoples preconceptions.