From undergrad to grad school, I've lived and studied in six countries: China, Japan, Sweden, France, Germany, and the US. The research/lab cultures and education systems are quite different between these countries, and one of the biggest differences I have noticed is how professors of different countries will write a recommendation letter so very differently, even if they liked the student equally. For instance, I knew my PI in Germany is very "concise and factual", and she will write a good recommendation letter for me in her standard, but I also know it will be way too short and "plain" in the US standard, and it worried me. My impression of recommendation letters written by US profs is that they are usually very elaborated and I've been told that there's a certain set of "code" in the rec letter that people need to know them to understand what they really meant.
For example:
A is a good student actually means A is not as good/average;
A is an outstanding student means A is a good student;
A is one of the most outstanding students during my XX years of teaching at XX University means A indeed is an outstanding student.
I also saw this tweet on twitter recently and it generated a lot of discussions - some people completely agree, some people thinking four pages of the recommendation letter is crazy and not useful. And these different opinions worry me, because it seems like invisible barriers for students who want to study in another country.
What's your thought on this and/or recommendation letters in general?