Making all immersions strengthen words
Whenever Duo tells me that I can now translate such-and-some-% of immersion articles and I help translate the suggested article and it strengthens my words, I always fancy the thought of all articles strengthening words.
But all immersion do strenghten your words - go look att you vocabulary after you translated something lots of words will have been strenthened.
Personally, I wouldn't like that. Immersion doesn't really help me remember words like practice does, but I like translating and I wouldn't want to have to cut back for fear of altering the already imperfect word strength/practice algorithm. I think it's nice that we have a choice.