Reviews mix up radicals, kanji, and vocabulary. They also mix up their readings and meanings in with other items.

Why?

It’s a little harder this way, but it’s way better for your memory.

It has been shown that when you study different (but similar) things together, you are going to remember more of what you studied. This is called “interleaving.” There are a couple of reasons for this:

1. Interleaving helps you to make connections. In one review, you will see a radical. Then, you will review a kanji soon after, and realize that it uses the radical you just saw. Later in your review you see two vocabulary words that use the kanji you just reviewed. This way radicals, kanji, and vocabulary aren’t separate things. They are a greater part of the whole. These connections reinforce the individual items in your brain, and create more ways to access each memory.

2. Interleaving also helps to prevent “review hypnosis.” By repeating the same type of thing over and over again, your eyes gloss over and you stop learning. By interleaving, you have to pay attention to what type of answer you need to put in. This keeps your brain active, which helps you to actively learn.

You can read more about interleaving here.