The gradual cooling method works the same way as all the others. The solubility of 4mmc at a lower temperature drops and the crystal begins to grow. The slower the temperature changes, the larger the crystal grows.
One disadvantage is that even after crystallization is complete, some 4mmc remains in the water. Therefore, it is better to use two solvents.
A large percentage of water and a lower percentage of solvent will create perfect crystals and the solvent will retain and save the rest of the product for later extraction.
X-ray diffraction pattern would make this more convincing (haven't seen such 4MMC since 2010, therefore I know they can be as such but I never personally obtained them). P.S. I haven't got any actual competence in interpreting XRD data...