In my experience, it's not true of undergrad studies. It is however (again from my experience) very true at the graduate level. Typically because of the grade c

In my experience, it's not true of undergrad studies. It is however (again from my experience) very true at the graduate level. Typically because of the grade compression at grad school - in most cases a C+ is a failing grade, thus the range of acceptable grades is compressed (undergrad A-F, grad A-C+). So a grad B+ takes on the characteristics of a undergrad C+ - essentially a signal that you need to shape up.