When I wrote this short note in 2022, the question I was asked most often was whether learning German is more like a sprint or more like a marathon. The honest answer, after nearly two decades of teaching adult learners in London, is closer to the second — but the more useful question is not which metaphor fits. It is what timelines you can realistically expect at each level, and what determines whether you actually hit them.
I have since written a much fuller answer.
If you are trying to work out how quickly you will progress to A1, A2 or B1 — and what separates the students who reach those levels on time from the ones who fall short — please read my updated article: Realistic timelines for adult learners of German.
It draws on the same teaching experience but with concrete numbers, the variables that matter most, and an honest view of where the majority of learners actually stall.