Present perfect/present perfect progressive (QUANTITY VS. DURATION)

I have been learning at HCC since last month.     EMPHASIS ON DURATION
I have learned a lot of English since last month.      EMPHASIS ON QUANTITY
I have been driving for 3 hours .        EMPHASIS ON DURATION
I have driven 200 miles.          EMPHASIS ON QUANTITY 
I have been reading this book for days.EMPHASIS ON DURATION
I have read 300 pages so far.          EMPHASIS ON QUANTITY