Yay, glad you like it! I also found most tools to be too black and white. I made Intention to be the sweet middle path between blocking sites entirely and having unfettered access.

I can definitely relate to the unpleasantness of getting kicked out with no warning, so I included intelligent logic in Intention that handles cases gracefully. For example, on YouTube, it'll pause the current video when the lock activates but it won't pause the video if it's in a background tab so people can listen to music. Hopefully, you won't even notice these things and everything will Just Work.

Enjoy. :)