Comment by runarberg

I would imagine there is probably some reverse S-curve of skill loss going on. The first year you may retain like 90% (and the 10% are obscure words, rare grammar structures, expressions, etc.), then in the next 2 years you loose more and more every year, and by the 3rd year you’ve lost like 50% of the language, including some common words, useful grammar structures, but retain common greetings, basic structures, etc. and then after like year 5 the regression starts to slow down and by year 10 you may still know 20%, but it is the most basic stuff, and you won‘t be able to use the language in any meaningful way.