Different directions for different languages [SEP] Directions on my bottle say (in ENGLISH) Wet hair. Apply shampoo & massage onto hair & scalp. rinse with warm water.  There are two other set of directions in other languages and their directions both advise 15-20 minutes.  So do certain hair types need to leave the shampoo on for 15-20 but if you speak English and are possibly from the US you don't??  I am very put off about this because I have not been provided with ALL the directions on my bottle.