IMO, there are a lot of different scenarios that can be described as 'solo training'
E.g., someone with many decades of experience practicing and refining movements alone.
Someone who several times a week does regular on-the-mat training with an uke and an experienced teacher, adding some extra solo practice to cement movements between meetings with their teacher.
A beginner without regular frequent access to a teacher doing solo training.
IMO, all very different things, all very different consequences
True, but...not what I'm really talking about.