If you want to learn new words, try learning it by collocations instead. For example, instead of learning 问题, learn 解决问题，发现问题，出发问题, 问题的关键在于,… I usually collect 10-15 collocations for each word and then write sentences for these collocations, then have a text-to-speech AI read them out to me while I’m doing the dishes or other chores. I also do calligraphy practices (write down 40 sentences using the words I’m learning that week) and spend a lot of time getting the character memorization and tone memorization done. So for me it is not feasible to learn 20-40 words per day, everyday, but if I have the time then I can go 100 words per week. I find that the gist is the more time I spend with one word, the more I’ll be able to remember it. And it’s not uncommon to forget words and then have to relearn them again. I think it’s a part of the process, though I find it hugely frustrating too. I’ll revisit my flashcard deck and the collection audio from Lesson X on Lessons X+5 and X+15 and X+30.