Perhaps rarely "necessary", but happens quite a lot recently. http://www.dw.com/en/germany-to-mark-record-year-for-strikes/a-18450024 http://www.dw.com/en/germ

Perhaps rarely "necessary", but happens quite a lot recently. http://www.dw.com/en/germany-to-mark-record-year-for-strikes/a-18450024 http://www.dw.com/en/germany-to-mark-record-year-for-strikes...