I think this is a good idea. I almost asked for tracking of my progress and speed (words/second) in Blitz but decided I was already asking for too many things, and didn’t know if this would be generally useful to others. If I was learning multiple languages, or i was trying to balance different aspects of learning, the ability to track would absolutely make a difference for me. But, again, if you add this as a feature, hopefully allow people to opt out or streak freeze indefinitely. Right now, for example, I am pushing hard at Blitz and almost totally ignoring new reading. That balance will eventually change.