Methinks the mechanic was over-generalizing.

Shouldn't drive in 2nd gear too much in my 3-speed Ford Festiva, or did he mean I should stay out of second gear in my Audi with the 5-speed automatic? In my Audi with the 5-speed automatic, 2nd gear is bad but not 3rd? What about my Lexus IS300 with tiptronic, should I stay out of 2nd gear while driving that also?