Consider the phrase "Don't waste time with American literature." Is it legitimate to interpret it as meaning, spend your time cautiously while reading American literature, and don't spend too much time read it?
A definition of the word waste is "use or expend carelessly, extravagantly or to no purpose," which lends some credence to the second interpretation. But, idiomatically, "don't waste your time" in my experience always means "don't spend any time on."
Am I properly understanding the idiom? Or can one simply use the words "waste time" outside of an idiomatic context, valuing their denotations separately?--thereby making the above phrase a caution against spending time poorly, rather than not spending any. What would most listeners or readers understand the phrase to mean?