I discovered the Memrise website recently and this has consumed a great deal of my attention. It is another mostly free language memorization aide using spaced repetition. I wish I had discovered this 50 years earlier. My language interests span many languages, but the one that I have invested the most effort learning is Chinese. The frustrating point for me was that I have been stuck at an intermediate stage for decades. About one third of the needed traditional characters were committed to memory, but this isn't enough to read anything serious and then the mainland China simplified characters came along to clutter the picture. My study materials were too archaic, so they have all been tossed out. The ideal solution would be to quit my job and move to China for a year, but that is a non-starter once you have a family.
But then along came Memrise which has all the word memory lists that are stored in C-3PO for communication. For Chinese, it looks like they have a few hundred word lists, but the main ones of interest are the lists needed for the TOCFL and HSK exams, which are roughly equivalents of the TOEFL, but for foreigners moving to Taiwan or China intending to work or go to school. So now I am plowing through different traditional and simplified lists for these exams working my way back up from the beginning. The program keeps track of how often I use it and is now reporting that I have been continuously drilling for 27 days. There is still some lesser drilling going on with the Duolingo program which reports that I have been faithful for 92 days straight.
A nice thing about the lists is that they give an estimate of the number of hours of drill needed to complete each list, presumably based on the statistics developed from previous users. Then there is the pickiness of the program as it zaps me for each wrong keystroke as I type out the pinyin with tones for each character. For German, this works out to needing to type up to 50 or 60 keystrokes without making a mistake. At this point I have a few hundred hours of Chinese drill ahead to get where I want to be. This should keep me out of trouble for awhile.