TC3 all practice should be performance.
Absolutely not! Quite to the contrary. During performance, all bits have to be there. The notes should be correct, the rhythm, the phrasing, dynamics etc. If we would try to do all of that during all of our practice, we would never become any good.
In contrast, we should know what we focus on during our practice. First, learning the notes. For that, I use a Molly-inspired schedule of small parts that are learned in an interleaved manner. I may very well start by playing the notes non-legato even though they later need to be played legato, and I play tricky passages slower. Slowly add correct tempo, correct articulation, correct phrasing. When you hear something isn't right, step back and think about how you need to practise in order to fix this.
Only in the final stages of practising it should be like a performance. Then I record my playing, listen and try to figure out what needs more work - or I bring it to my teacher who will tell me, and then again, I will work with whatever it is that needs work.