[danaris]

There are multiple types of strikes.

Some are as you describe, but that's generally considered the last resort: those strikes are the pitched battles of labor wars.

It's much more common to have strikes with smaller scope and a defined endpoint, which are more or less warning shots. They show a) that the union is serious, b) that it has the support of its members to strike, and c) just how devastating it can be when they do so.

If teachers unions across the country were to coordinate a three-day strike, it would send an incredibly strong message to school boards and state departments of education—both directly, and indirectly through the collective screams of parents. (Unfortunately, at this point, any efforts to help teachers and improve public education are going to be seriously hamstrung by the Trump administration's destruction of the federal Department of Education.)