I think that I was able to figure out the needed idea in “Fill Again” just because it’s presented in a much simpler layout; I immediately parsed that since I needed those 4 squares filled, I would only have 3 boxes left to maintain a 2x2. I suppose in “Not Enough”, the idea did not immediately pop into my head since… I thought that there was a way to perhaps remove the box in the bottom right and replace it with a different box later (not sure what I was thinking there honestly). I mainly think that the clearer presentation of the “you do not have enough boxes for this to work unless you do something differently” of Fill Again was what gave me the idea.