Stub based on everything I've read, the spaced repetition should be much more effective but it's difficult to get away from my habit of blocked repetition.
I have recently started to try practicing something, moving on to something else, and then going back to the first thing before I end my practice in hopes of locking it in better!
I try to do more spaced repetitions than blocked repetitions, especially with new pieces that will be a bit of a challenge. I divide them into sections and make a Molly schedule. I don't take time though, but when I practise for half an hour, I aim for at least five or six sections. I find it hard to break though when I have the feeling that I don't "get it" it yet. I also don't know if it actually is a good idea to stop when you are in the middle of figuring something out.
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... feeling like the pianist on the Titanic ...
Whether it's blocked or spaced repetition, either is better than 'playing through,' which has been my bugaboo for a long time. Just thinking about doing blocked or spaced reps has helped me break the playing through habit. I try to save playing through for my reward at the end of practice.
Yes, I use it all the time. 
I think most people don't realize how small your practice chunks need to be to work effectively with spaced repetition. You have to work with chunks of like one or two measures, sometimes even sub-measure chunks if it's hard.
Here is how I do it. Let's say I have chunks A, B, C, D. I first practice each chunk separately for a couple of reps. Then, I play chunk A, pause, then chunk B immediately after. I do this a couple of times and then A+B without pausing. Then the same for B+C and C+D. At the end I might go back and play the whole section A+B+C+D with pauses or without. Each time I go back to a chunk it's like a spaced repetition with a greater interval since the last repetition. It happens automatically without having to calculate anything.
Again, take really small chunks. I still often make the mistake of thinking "Oh I can do this" and take a whole long phrase and practice that slowly, but it always ends up taking me WAY longer to learn it like that than if I break it down into one measure chunks and loop through it a bunch of times like I wrote above.
Stub Most of the time I use blocked repetition, but I've used spaced repetition for Molly Gebrian's performance practice. For that, I perform a piece "cold" at varying times during a day.
I'm glad you started this post. I'd forgotten spaced repetition in the context of performance practice. I've been trying to get a piece ready for a recital but was only doing a single "cold" performance play through once a week that was pretty much a train wreck.
Stub I think a question like this depends a lot on how long each passage is. If a passage is very short like one measure it might get too boring and hard to concentrate if one practiced it for 10 minutes in a row. I also think that knowing what one is doing or trying to do is incredibly more important than blocked repetition or spaced repetition or any other approach based on how long one practices a section etc. In the 10s of thousands of piano world threads on practicing this topic rarely if ever came up, and I think that's because it's not too significant.
There are lots of books about how to beat the sat test or crack in the sat that offer lots of tricks which may help a little bit. Many students like these books Because they view them as some magic bullet. But on the math SAT by far the most important thing is understanding the math. One can practice scales endlessly but without detailed instruction on the proper technique progress will be very slow or possibly reach a wall quickly.
If If one wants to use spaced repetition, I also think an order like A B C A B C A B C is perfectly reasonable. I also think most players would very reasonably spend more time whichever passages were more difficult and not be constrained by some arbitrary amount of time on a given section.
Depends on the piece I'd subdivide it into sections or small number of bars. Some technical pieces I'd be learning a bar that is giving me trouble on its own.
Never be tempted to play a section or the whole piece from top to bottom all the wrong notes are fixed.
BartK Here is how I do it. Let's say I have chunks A, B, C, D. I first practice each chunk separately for a couple of reps. Then, I play chunk A, pause, then chunk B immediately after. I do this a couple of times and then A+B without pausing. Then the same for B+C and C+D. At the end I might go back and play the whole section A+B+C+D with pauses or without. Each time I go back to a chunk it's like a spaced repetition with a greater interval since the last repetition. It happens automatically without having to calculate anything.
Again, take really small chunks. I still often make the mistake of thinking "Oh I can do this" and take a whole long phrase and practice that slowly, but it always ends up taking me WAY longer to learn it like that than if I break it down into one measure chunks and loop through it a bunch of times like I wrote above.
This is really helpful advice! It's hard for me not to want to bite off more than I can chew, but I'm going to try to be better about doing really small chunks.
Stub Same here, I like to reward myself for working hard by playing through at the end also. 
