Earlier quoted context omitted.
I think that is the point. It doesn't block the website entirely lest you go and disable the extension. It's designed to frustrate you slightly.
I see. Not very functional for those who have tabs for these sites permanently open.
But the block repeats every few hours, and I'm pretty sure that clicking on a link within the same tab repeats the block then (maybe depends on the page). So yes, the "dosage" of how many delays you get is not very well controlled for. Still, I'm using this setup for years and it definitely does something for me.