How to structure your practice!

How would you structure your practice if you have a lot of varying repertoire that you have to keep at a high level?

I have been reading about "interleaving practice." Have you used this in your own practicing and/or with your students? What do you think about this concept, and do you believe it works?

As an intermediate player,  along with the questions you posed (i.e. how long to spend on scales, etudes etc) I am also  wondering how long to spend on each practice piece?  I usually have three that I am working on at various challenging levels.  So the question is two fold, how long to spend on each piece (especially if I am focused on one or two challenging elements) and is there an optimum amount of time to spend on each piece to get the most out of the practice?   Is there a point where spending too much time on a piece or passages results in a diminishing return?    Really looking forward to this live event!  Thanks.

Please also address late beginner practice routines. I find that you don't have many materials catering to the beginner levels. 

My question is similar: how to structure the practice with different activities (scales, fingering exercises and études) along with the repertoire that I am working on. Also, how to zoom in on a different passage that I’m struggling either with techniques or interpretations.
Lastly, I was told not to just play a working piece from beginning to the end during practice and after years I am still struggling with ridding that habit. Any suggestions?

Thank you. 

I'm interested in everything that the community have already suggested, plus any suggestions on how to organise my practice "stuff"... I have papers all over the place, and my practice is a bit random! I'm sure there is a more strategic and effective approach to practice, and would love to hear about your own practice system. Also how can we best track progress, and set realistic goals for our practice session. This is such a huge topic, thank you for helping us to focus on it with this live session.

When I'm working on a new piece, I first work weeks (!!) on memorizing it, and then once I have it memorized I start really working on the technique.  Is that the right order - or should I first get the technique into my fingers while reading the score, and do memorizing later? What do you find is the most effective way to learn and memorize? 

When learning a new project piece, i.e. something above my current level, how much time should I spend on this piece during any one practice session? When in the practice session should I schedule this new piece? 

Because of work I am not able to attend some of the lessons Live so I watch them later.

This was another wonderful Live Stream! Thank you to everyone who asked excellent questions! Thank you, Dominic, for your expertise, clarity, passion and vision! Superb!