So...i guess I'm asking (a bit redundantly)...any interesting milestones along these lines? ...or not along these lines?
Hope you're all doing well.
I cannot say that I've ever done what you describe except when taking a trip with family and was unable to find a dojo to train in on that trip. So the longest I've ever been off the mat is perhaps a couple of weeks.
However, being a bit OCD, I have found that I make plenty of progress and discoveries about my training during these times and when returning. A lot of study can be done solo while visualizing a partner. It does not replace training with real partners, but is actually vital at various stages of practice.