No it sends the message that they can do it. And that is massive all on its own.
It's designed to bring them to the table without starving the workers. Indefinite strikes would obviously be more effective but then you're forgetting about the people who do need the jobs.
How many people can actually survive not working for months? Principles are great but so is paying rent.
If nothing changes they can just do it again and at a time that hurts them most. Like election week.