the idea makes sense (more water)...but the point is....why use shampoo or anything soapy as a windshield washer to begin with it all.
if it is available in pakistan, the best is to use specially designed wisdshiled washer fluid...that is resistant to all kinds of temperature...this advice is valid only if you have the stuff available locally.
pakistani climate is on the extreme...its hot and humid so plain water will simply dry up. over here....its the other end of the extreme...plain water will simply freeze during the winter...so the good humans came up with the temperature resistant solution.
secondly..i think the wiper blades do not have enough squeezing power to properly clean the windshield...plus they dont clean it all anyway...so you will be doing the job or getting it done later anyway.
just my 2 cents