I have been a user of Skritter for about ten years now, I think that makes me eligible for the occasional moan (every five years or so maybe).
I find it a bit frustrating that every time I use Skritter I seem to spend two thirds of the time drawing characters that I already learned. We are all here because we love learning Chinese (or Japanese) and we want to study, but especially we want to learn the characters and words we keep getting wrong. So many times I log in to Skritter and it throws up some word, maybe involving slightly unusual characters that I didn’t see for six moths, and I get it completely RIGHT the first time. But then the Skritter algorithm makes sure it comes up again every day for the next three days testing and even a week later. I remembered the word perfectly after six months!! That means I know it!! So why keep asking me for the next three days?? The really frustrating thing is that the third time I get asked I end up getting it wrong because I am rushing so much to get through the questions and then it gets added back into the pack on that basis.
The algorithm seems to be set to make me work for about an hour in real time every day. That is very hard to achieve in practical terms. I should point out that I am using Skritter primarily to learn characters, not to learn words. Every day when I come to Skritter I already spent an hour testing using a different program that lets me type in the the answers in Chinese, because obviously learning words and learning characters are two different things. I wish there was some mode in Skritter where I could tell it that a) I am learning characters not words and b) I only wanted to be tested for ten minutes on the stuff I keep getting wrong, not thirty minutes or an hour on the stuff that I mostly get right.
Maybe what I am asking for is a bit specialized, but just giving people the basic option to set out how much time they have each day for testing would be a really nice feature. It is counterproductive to have to rush through tests every day just to stop them piling up the next day, you end up rushing and cheating, it would be much better to let people do their five or ten minutes of obligatory testing then let them do twenty minutes of voluntary testing as happy bunnies than force them to do thirty minutes or an hour every day (the ambiguity is because thirty minutes of the Skritter clock is very often sixty minutes in real life) where they rush and cheat their way through. In real life we have jobs and study and a hundred other responsibilities to get on with! Please go a bit more easy on us!