This is a good heads up, BUT should be taken with a grain of salt. There are many left turn lanes in Mexico, retornos or turn arounds that are really overpasses that allow you to cross over and go back the other way.
Basically the old advice of expect anything is not really relevant You need to expect EVERYTHING.
Having said that driving in Mexico as in other countries in South and Central America is a piece of cake compared to many places I have lived or traveled...Try Egypt, Cambodia, Sri Lanka, Sierra Leone...these placs make Mexican traffic look like the well ordered streets of Zurich or Geneva.
There is really nothing so strange about Mexican driving or rules that you cannot pick it up in a few days (or sooner) by just doing it and paying attention.