The most effective method of protesting would be to find a way to get the masses to turn against the lawmakers in such a way that they convince the lawmakers to solve the problem that the protest is focused against.
But most of these protests just piss off the masses. They run their day with traffic, they destroy heritage sites that people care about, and while they do get in the news and get some publicity, people's memory is quite negative. And there are zero focus on anybody who could actually change the situation.