It depends on your definition o "weekend". The time allotted between Friday at the end of work to Monday start of work is technically correct.
However, when you come back to work on Monday, a frequently asked question is, "How was your weekend?" That indicates each person has a different weekend, even though everyone shared the same time span.
I would say, personally, "weekend" because I recognize it hasn't happened, yet, so currently the individual weekends of each person have not occurred, yet.
If several people told me of their plans for the weekend, their weekends exist, if only in the idea stage. In this case, I would say, "weekends".