Forget the "6 month rule". U.S. Permanent Residence is a "Use it or Lose it" benefit; period.
Many residents falsely believe that so long as they enter the U.S. once every six months, they will be able to retain their permanent residence privileges indefinitely. However, that's a colossal misreading of U.S. law.
Photo by MJ Tangonan on Unsplash. (Austin, Texas). The privilege of U.S. permanent residence can be rescinded when a U.S. Customs & Border Protection officer factually determines that an applicant for admission has abandoned USA and can no longer plausibly refer to it as "home". Even if a permanent resident returns to the U.S. every six months, excessive trips abroad of substantial duration can lead to being summoned before an Immigration Judge. While it's true that the "6-month rule" allows a CBP officer to automatically presume that you've abandoned the U.S. as your home if you've been abroad for more than 6 months, that presumption can still be reached even if you've had frequent trips abroad of shorter but significant duration.
For information on how to become a U.S. permanent Resident, read my blog post titled "The 4 Routes to U.S. Permanent Residence." Feel free to leave helpful comments at the bottom, especially if you think that they may help other readers.