Nothing to do with “thin layers or film” left on mask. Either it fills the microcavities or it doesn’t. Viscosity seems less important than the chemistry. If 100% works for you - great. I only use 20% - works for me.
Why do I very often get fogging with even a 50% solution but not 100%? Science says there has to be a ratio and method that works for everyone, right? Do you rub your 20% into the lenses, then rinse?