OK, so I decided to write an extension of this explanation, which you might want to read first, if you’re not already familiar with it.
Here’s the deal. What’s the usual way you try to remember, say a Chinese character (kanji, hanzi, whatever)? Write it out a kajillion times, right? Brutal, medieval, ineffective. That may have worked for Frances Xavier with oodles of time and church money, but it won’t work for the kid like you or me who wants to actually learn something to a high level in a practical amount of time. By practical I mean “only a fraction of the number of years you have been alive”.
By now you’re asking: “what snake oil are you selling, Khatzumoto?”. Shut up and listen.
That kanji that you’re trying to break your arm with by writing over and over again? You’re probably going to forget it tomorrow. By next week, that sucker will be gone. Not because of some wicked, intentional long-term social engineering project to make kanji difficult and keep the masses illiterate (a load of bull, by the way, especially since some of the most literate societies in the world were and are kanji-using societies), but because of the nature of human memory. Besides, you don’t truly need to remember that kanji tomorrow, but in 6 days, and 6 months and 6 years.
Why do you remember your own name? Because your mother sat you down one day and said it to you a thousand times until it had been indelibly etched into your little toddler memory? Because your name is special and powerful and beautiful and unique? No, and, no.
You have heard, read, written and said your name many times, not all at once but spread out over time. That’s the key to remembering something. Not cramming–not concentrating repetitions, but spacing them. Basically, if you hear or read something at the right spacing over time, you will remember it better and better. And the cool thing is that this spacing grows over a time. After a while, this space of time can grow so long as to go beyond the duration of your natural life. Put simply, even if you stopped writing, saying and hearing your own name today, and didn’t hear it again until the day before you died, you would probably still remember it.
How do you get something repeated to you over time until it’s as natural to you as your name? Well, you can do all the time and spacing management/calculations by yourself, or you can get a program to do it for you. That kind of program is called an SRS (spaced repetition system). It will choose when to show you (test you on) information.
If you want to remember that kanji, you need to review it today…tomorrow…in a week…in 2 weeks…in a month, and so on. You need to practice gradually over time, not binge on it. Writing out kanji hundreds of times is good for practicing your form and stroke order, it will help you get nice-looking kanji (it helped me), but it’s l-o-u-s-y for memorization.
Which SRS should you use? It doesn’t matter. They all basically do the same thing. Just use one.