You can work for 20 days at making a post, 8 hours a day, that will have no value. It isn't labor that creates value if that labor isn't directed at making a product of value.

If the post you make that takes 160 hours consists of 10010001001010100 it will be valued according to the subjective benefits perceived by the consumers - curators in this instance. It will likely have 0 value.

If you post an incredibly insightful poem, or new item, even if it takes you little labor, it can have great value, even save lives.

The labor may be necessary to produce goods, but is only valuable in relation to the necessity and utility of the good.