My German teacher at school did an accelerated course from scratch at university (no previous knowledge) - a full language degree. It involved rote memorisation of German texts. It worked! She said that the advantage was that you later recognised phrases and grammar and were able to analyse what was previously just rote memorisation.
I spent a couple of years in Italy in my early 20s and learnt fluent Italian in that time. I took a couple of classes a week in the evenings, but spent the day programming with a team of English colleagues and perforce spoke English. I made an effort to socialise with Italians outside of work.
I went out with groups of Italians many a time, and experienced many a boring evening where if people didn't speak to me specifically I couldn't understand a thing.
I realised that after 9 months I could hold a good 1-to-1 conversation but that it was another 9 months before I was comfortable in a group situation - in your native tongue you can keep tabs on the various threads of a group conversation with ease, whereas if you are having to explicitly process it, it's so easy to fall behind and then you're lost.
From experience with exchange students, staying with families and going to regular local secondary school (ages 15-18, look at www.afs.org for more information) -- that sounds typical for an adult in a non-native work setting, making an effort.
Generally students starting at zero will use 3/5/7 months to approach fluency, approaching native level at the end of a stay. The difference being the "jump distance" -- so German to Norwegian or Spanish to Italian is 3 -- Arabic to Norwegian might be 5 -- and Japanese to Norwegian might be closer to 7.
Coming to Norway, sometimes students with poor English skills will do better - not being tempted to fall back to English, breaking the immersion - and not having such a hard time "forcing" class mates to speak Norwegian.
Having spent a year in Japan myself, it's fascinating how one can go from seemingly "nothing" to fluent after those months of no apparent progress. But language learning tends to be like a staircase -- you can feel stuck at one level for a long time (and being in a foreign setting it can be incredibly frustrating to be constrained to a preschool level of speech) -- only to seem to jump up a level. And then you'll be stuck there... etc
I spent a couple of years in Italy in my early 20s and learnt fluent Italian in that time. I took a couple of classes a week in the evenings, but spent the day programming with a team of English colleagues and perforce spoke English. I made an effort to socialise with Italians outside of work.
I went out with groups of Italians many a time, and experienced many a boring evening where if people didn't speak to me specifically I couldn't understand a thing.
I realised that after 9 months I could hold a good 1-to-1 conversation but that it was another 9 months before I was comfortable in a group situation - in your native tongue you can keep tabs on the various threads of a group conversation with ease, whereas if you are having to explicitly process it, it's so easy to fall behind and then you're lost.