Spaced repetition is underrated. I still remember a lot from my cards despite not having studied them for years
I had the opposite experience. If something's easy to remember, I don't need Anki. If something's hard to remember (I really struggle with birthdays, for example), even Anki doesn't help! The cards all end up as "leech" and Anki stops showing them to me. (I found this behaviour amusing, since the whole point of using Anki is to help me learn things that are difficult to remember!) They say if a card is ending up as a…
That probably depends on what and how much you are trying to memorize with Anki. It is easy to learn a few words in a foreign language, but try to learn three to five new words per day for a year straight and suddenly you realize how far spaced repetition can bring you.
For leeches, what helps is to create more cards with the same concept (and do not suspend the leech, you are right that is not a good idea). If I struggle learning a word, I create more sentences using that word, or connect it with synonyms and antonyms. For birthdays, maybe try to add some memories related to that birthday: some particular gift, a happy moment during that day, the weather or location where you celebrated... Just see what sticks :)