Self-study
I find that my previous memories and a mental freeze prevent it from being of any use. Which makes it harder as the 6 minutes runs out quick. I don't have this issue nearly as much with longer sections of hard questions, I have a better control of time then.
I've just started skipping them altogether. I much prefer doing very thorough BRs and moving on.
great way to warm up after a studying slump on a busy workweek, loved this!