The following training method is not recommended for beginners in the martial arts. In the real world you don't control what kind of environment you might be in when trouble rears its ugly head. You could be on a slippery floor or ground when you have to defend yourself. As such it sometimes might be a good idea to train on slippery surfaces, a wet tiled floor for example. This training method can be dangerous and its only recommended for experienced martial arts practitioners and people who know how to properly fall. Doing kicking drills on slippery surfaces can be particularly dangerous and is only recommended for people who have experience doing proper break falls in case you do fall since there is a much greater risk of falling when you do kicking drills on slippery surfaces as opposed to hand striking drills. As this training method can be dangerous it can also be important in case you ever are in an environment where you're standing on a slippery surface and you have to defend yourself. Disclaimer: Do this training method at your own risk. It is only recommended for people with good experience in the martial arts including being able to properly fall. I take no responsibility for anybody who gets hurt when they try out this training method.