No. It depends on what type of server you are on, as well as the weapon / armour.
If you are on the PvP server, we have different gamemodes for 1.8 in the 1.9 client — as a result, damage will be significantly higher from spam clicking.
However, if you are on anywhere else, it uses the 1.9 style - you need to time your hits. Spam clicking does work at times, but that’s all dependant on their weapon and your armour equipped. Try it yourself and see if it works for you. :P