How detrimental are long breaks (2-3 months) of complete absence of study? Between these breaks periods of about 1 month of intensive study then another break.
long breaks
I wouldn't recomend that study plan, but I have found the occasional break to be beneficial. I've just taken a 3 week break from French and I found that my listening comprehension had improved.
I think it depends on the person. Are you the kind of person who "dumps" information quickly? If so, I wouldn't recommend the break. If you retain information, it doesn't matter imo. I've been away from languages and picked them back up quickly and I am not a genius.