When I purchased my house in 1991, the low-flow heads were required. As soon as I moved in, the reinstallation of the old, dingy, yellow, high-flow heads was my first priority.
I have very very thick hair, and it would take me quadruple-time rinsing the shampoo and conditioner with those low-flow heads.
Interesting enough, there were 2 'new' low-flow heads that I recently read last week. I was going to buy one as a trial to conserve water. I need to save $$ to buy 87 octane