Cephalopod
Green Belt
Granted.This is true. Static training is not the same as dynamic training, and solo training cannot replicate working with a partner who can apply unanticipated force to test your stance.
The interesting question that this thread has raised, however, is how can you make best use of solo training to improve your stability under duress.
As I'm lucky enough to have people to frequently train with, it is hard for me to measure exactly how much benefit I have gleaned from the solo training I do at home. But I still feel that it is significant.
I know beyond a doubt that my increase in stability over recent years has not come from getting stronger legs (yep, I'm still pretty scrawny and I ain't getting any younger) but rather from increased mindfulness of the engagement of my core. (That, and I've gotten better and not letting people apply force directly onto my center, but that's a separate topic)
In the pursuit of said mindfulness I have made it a habit to practice this awareness when I do chores about the house. For example, when I open the utensil drawer, previously I would always stoop slightly (curve the spine forward) to reach the drawer. Now, I keep the core engaged and bend slightly at the knees to reach the drawer. Similarly, when I open and close a heavy door at work, rather then flexing my shoulder and tilting at the hip to deliver force, I relax my shoulder, engage my core and do the work entirely with my legs.
The more I practice these silly sounding habits, the more I find myself doing them without thinking.
For myself I have no doubt that the stability trained like this on my own has translated to better stability under forces from a partner. Sure, there's other aspects that can only be trained with a partner such as sensitivity to where said forces are directed, and timing. But for me that partner training builds on a foundation of mindfulness to not let the core tilt and buckle, but rather efficiently translate the force through the body to the ground.