I trained in Yoshinkan aikido for several years earning my 1st kyu rank under Stephen Ohlman. The first time I tried to practice aikido outside I was shocked to find that the wonderfully gliding and sliding footwork I'd been doing failed me. Asphalt is a generally unforgiving surface and I could break-fall on it without issue but the raised stones kept catching on my shoes. I had a similar experience when I tried the footwork on a lumpy soccer field.
A year or so later I watched an amatuer boxer from my high-school get knocked out by a kid with zero experience fighting. The boxer kept trying to push off his toes to generate power which left him slipping and his punches empty. The arm-punching inexperienced kid stood with flat feet and just swung.
I'm telling you these stories to prove a point. No matter how good your training is if you want to be able to apply your skills effectively in the real world training for that environment is important. Today I want to highlight one key aspect on environment: ground. Both myself and the amateur were unprepared for ground outside of training. Thankfully I clued in and was able to adjust my training before I had a similarly unfortunate experience.
In case you're not aware wherever you train has been set up to be a relatively safe and stable environment. The ground is always the same whether it is padding, tatami, or hardwood, it doesn't change from day to day. Unfortunately we don't always get to pick the time and place of our encounters with danger. You can reduce this disadvantage somewhat by training on different surfaces. In a 30 second walk from and including my apartment I found: dirt, gravel, grass, rough asphalt, smooth asphalt, concrete, tile, carpet, and hardwood. Each of these surfaces is different in terms of give, friction, grade and sometimes even slope.
If the UFC decided tomorrow that they were going to make the floor of the octagon more grippy or more slippery you can bet that pro MMA gyms around the globe would be doing the same to their flooring. Why? Because you practice the way you play. I'm not saying you have to become the artisan of asphalt or the god of grass but it does make sense to practice on real world surface from time to time. Lumpy grass isn't level and you have to lift your feet a little more. Sand requires more push from the toes to generate power. Snow, ice, and dirty or wet tiles are slippery. Asphalt is hard and rough. Grass is not always a flat surface and fighting on graded and/or pitted ground is not the same as fighting on flat ground.
I would not suggest doing this every day and caution is needed when working on hard surfaces. You have to learn to respect that hard ground can mean fractured or broken bones even from an accidental fall not to mention throws, takedowns, and knockdowns. If Sun Tzu saw fit to dedicate an entire chapter of The Art of War to terrain I suggest that it would be a good idea to familiarize yourself with the nuances of the ground outside of your school.