I believe that a true revolutionary wants that radical change as soon as possible, but realizes that it takes time to do so. Instead of burning out in a blaze of glory, revolutionaries need a 'slow burn' in order to build both legal and underground networks and structures. To raise revolutionary levels of consciousness among the public and to raise the level of participation in revolutionary movements.
In essence, revolutionaries need to create a base. To do so, they can use their own propaganda, but ultimately must learn from the natural progressive instincts of the people.
The impatience of many who yearn for revolution leads them to become apocalyptic in their scenarios of the continuation of the capitalist regime, while becoming utopian about their visions of the post-revolutionary society.
True, there is much to worry about in allowing the current state of affairs to continue. Yes, conditions change fast, and it can be tempting to make the revolutionary movement move faster than it is able to. However, the lessons of the great texts of war, Sun Tzu's The Art of War, Mao Zedong's Guerrilla War and Che Guevara's Guerrilla War, all repeat the same theme- only fight when you can win.
On one issue though, there is the fear that waiting will mean no such opportunity to ever have a revolution, because the apocalyptic threat is that real. The issue is of course the environment. Global warming and the threat of nuclear annihilation raise the question, 'will there be a world left for the revolution?' Whether we like it or not, we have no option but to take the slow burn approach since a faster “revolution now” approach will fail.
Is there a need for a leftist revolution now? Yes, but there was a need for one yesterday, the year before, and going back to 1886, 1860, 1776, 1492, etc. It's better to know concretely what we are for, what we are against, and how we are going to get there, than to lash out without strategy.
Many Anarchists turn to propaganda by the deed to move the revolution forward. Propaganda by the deed is a necessary thing, it can inspire many people, but it is best if such militant actions take place as one tactic of many in part of a coordinated movement. Some might complain that this violates individual initiative. But societal change of the kind we want does not just happen by a few small people's will. Imagine a workplace. If you are the only person who goes on strike, then you will be fired and nothing will significantly change. If you take the time to build up your union, and then everyone at work goes on strike at once, the impact will be that much more powerful.