Random flow drills can be done at both the isolation and integration phases of training. They're characterized by having random elements with a level of cooperation. It's the level of cooperation that leads to the "flowing", in comparison to blasting and crashing inherent in other types of drills. Unlike entirely prearranged drills, they are either partially or entirely random. But unlike sparring, they are partially cooperative instead of being entirely competitive.
Random flow drills are an excellent bridge between prearranged drilling and full sparring, fighting, or real self defense. They can be trained at any level of intensity, with a great variety of goals and purposes.
As mentioned on my stick and sword page, although versions of random flowing can be found in a variety of styles, I was turned on to the variations and value of the method by Maija Soderholm's material on Visayan Eskrima. Here's a great post she wrote on going further down the bridge connecting drilling and sparring.
Isolated random flowing involves limiting drills to particular pieces of "fighting". See the following as examples:
In the above examples, person A can be limited to making a simple attack, or can be allowed to fake or otherwise trick person B. Different layers, goals, and purposes can be trained with isolated random flowing, and it can be done with or without weapons.
Random flowing can also be done at the integration phase of training. At this level there are no limitations on the techniques that can be used, but there is a level of cooperation to facilitate learning in an environment safer than full sparring.
- See more on self defense training.