People do it all the time because it's fun and you get the initial kick. Like planning a budget, habits, hobby, exercise routine or spend a week collecting courses. Then the daily grind starts and you give up after a few days.
I, personally, just am reading a novel series Japanese, 8 books in. While reading, I have highlighted all the words/parts I didn't know in order to export them and make flashcards out of them. I haven't still started going through them, but the thought of doing so feels laborious, so procrastinating is bound to happen.
Finnish is a second language to me and what I've found better than flash cards is to just write down words I don't know as I'm reading. Initially this can seem terribkt slow because each book with have its own vocabularly set. As I continue if I read a word I don't know zi scan the list briefly. If it isn't there or I fail to see it I write it down again.
If you do not have time to study... I had to do long commutes while working part-time to get my CS degree.
Sometimes I was left with only 1 day of study for an exam and this was the best method for me.
