I don’t think there is a set criteria for “over training” other than ‘are you hurting yourself’. I think the idea of over training is more prevalent in weight lifting because, by nature, it’s more dangerous and strenuous on your body. People tend to take that idea and apply it to other training methods.
I’d say as long as you aren’t working hurt muscles and aren’t trying movements beyond your strengths every day you should be fine.
I’m still working on assisted pistols which are difficult for me. If I did a set of them, or tried regular pistols every day im sure my knees would be killing me.
So yeah…in my humble opinion, I don’t believe you can over train without knowing it.