Leechblock is excellent. I presently use it to block facebook (except for events and permalinks to specific posts) all the time except for 10min between 10pm and midnight; I have a list of webcomics that I can only view on saturdays; there is a web-based game that I can play once every saturday (whereafter the expired time prevents me from playing a second game), etc.
You can use leechblock to add time restrictions for any site.
It also has the option to add loading delays to sites, which I find useful for sites which I can’t afford to block outright.
Leechblock is excellent. I presently use it to block facebook (except for events and permalinks to specific posts) all the time except for 10min between 10pm and midnight; I have a list of webcomics that I can only view on saturdays; there is a web-based game that I can play once every saturday (whereafter the expired time prevents me from playing a second game), etc.