As part of preparedness for battle, which could come at any time, even, say, when one was on the toilet:
The method his master taught for relieving oneself had been passed down for generations untold. When one would go to the outhouse, he would remove his right leg fully from his clothes. This was to give him full mobility. Yes, it would be odd to fight someone off when you were on the john, but imagine your feet being tied together when you were attacked on said john vs. your legs moving freely.
Secondly was body position and posture. The samurai would sit squarely on the seat, cross his leg so that his right ankle rested on his left knee (his left foot remained on the ground), place a hand on each knee, then straighten his back. Supposedly this aligns the bowels to help one from having to strain. You may think it seems like a bunch of malarkey, but this one actually works. If you have ever felt like there is a plumbing issue when you sit down, then pay attention. Take your time, have some patience, and you will get the yoga version of Draino on your system that has been passed down from samurai warlords of old. I have literally felt a swirling sensation during the act of evacuation. Try it out to see for yourself.
One downside is that our toilet seats are really geared towards sitting with both legs straight forward and on the ground. Another is that rarely is the seat exactly where your thigh is parallel to the ground. Most seats are too low for the average man, so it may be a strain just to get that leg up. Finally, if you really want to be technically correct in what you’re doing, you need to have a bokken in the bathroom with you. This is part of being prepared. Legs free is good. Legs free and armed is better.