Max duration Student Visa only 2 years

Recently I have read that the maximum duration of a student visa for a language school is 2 years, which makes sense since longest courses you can find are 2 years.
However, here it gets fishy. Seems 2 years is the maximum time for life. So in other words if you have studied at language school already for 1 year in the past and want to come back to study again at a language school you can only do it for 1 year. Like 1+1 = 2 time limit over.
Wondering if that can be really be true. Found that info on study.gaijinpot.com
After reading that, I contacted the staff from gogonihon and they claim also 2 years max for life time.

Seems there 2 types of student visa: college/university and language school.
2 years + life them is for the second type.

Also here I start wondering if the maximum length for the university type which is 4 years and 3 months is again for life. That could be a problem if u have been to Japan as exchange student which should count as University type visa for 1 years because then you have to finish university in only 3 years and 3 months.

That seems quite unlikely, but it could be possible. You will have to contact immigration directly to know for sure. I imagine that there is a limit for renewals for students who stay in a particular course, but plenty of students go on to regular universities or technical schools after studying at a language school, and many students go from there to higher levels of education. It's all a matter of keeping the immigration office informed about your school location and attendance status. Searching in Japanese, I did see a couple of language schools that mentioned a maximum length of 2 years and 3 months, but it didn't say anything about a lifetime limit.

Got this answer today from GaijinPot:

Thank you for your interest in studying in Japan. The 2 year limit is for life and everything is tracked by the government, so even if you change schools you cannot exceed 2 years. If you go to a university or some other class of school then you can extend it, but language schools are highly regulated in this way.

Still wondering where is the written law of that or is it oral.

There is no written law saying that.

Rather than asking Gaijinpot, you should contact immigration. They are the only ones who can give you authoritative answers.