TIME SENTENCES

There are 2 types of time sentences:

1: ON A DAY, e.g., I'm going to study on Monday, on Saturday, on the weekend (some time Saturday or Sunday or both). The road will be closed on the weekend.

2: FOR A PERIOD OF TIME, e.g., I'm going to study for 5 minutes, for 2 hours, for the weekend (all 2 days). The road will be closed for the weekend.

so 'weekend' can be used with both 'on' and 'for'.