I haven't been using Web Rules because the couple times I tried it, it didn't go well. When I stopped the session of Web Rules it still didn't allow the students to get back to their sites that were blocked from the session. They refreshed and it still said blocked. I found a minimal work around by having them click back. However, they lost any progress in the tabs they had been working on before they were blocked. I have seen this work efficiently in GoGuardian.