This has the potential to be a very useful program, but its fundamental operational principles are not well-documented: when you specify the amount of time you want to be internet-free, you are not specifying a countdown, but rather the actual amount of time your computer will be used before networking is restored. In other words, if it is 2pm when you specify 2 hours, your computer will only have networking restored at 4pm if you've actually used your computer for 2 hours during that time. Since sleep does not count toward computer usage, you never know exactly when networking will return.
When I inquired about this, the developer replied that this was a design decision and would not be changed. The program should accommodate both the current approach and a simpler one, where the user specifies a time interval during which networking isn't available (say 2-4pm). Since the developer is not responsive to this need, I would not contribute money this project.