I don't know, Ringer, I'll come back when I know, but here's my guess:

The union has to decide where to strike. Assume that in VW they had 75% for the strike and in Mercedes 90%. So they would start there, wouldn't they?

That could explain it, but there's another reason I guess is more probable. At the start of the strikes they don't strike in all of the country but only at some selected plants, as a kind of threat. This way it is cheaper for the union. But they take turns, for none of the workers wants to damage the ability of their own plant to compete. So tomorrow you may see VW and BMW strinking and the others back on work. Two days later, teh steel workers...The union doesn't want the damage to be selective.

These strikes are only demonstrations of strength and preparedness yet and not real strikes. After a couple of more weeks without successful negotiations there could be strikes which last longer than just one shift and afflict more than just some selected plants. But that will not happen. They'll come to terms before that.

Wolfgang