I have the same It's George 2x4 as my daily case for over 10 years. I bought it pre-owned, so it could easily be 30 years old. No daily maintenance required. When I remember or notice it to be dusty or dirty, I wipe it down with damp cloth.
If you have leather case that needs tender loving care, you should ask yourself. Do you know the difference between veg tan oak and goatskin Nappa? Neets foot oil versus Lexol? If not, seek good advice, such as from a shoe repair shop. They deal with shoes, handbags and luggage repair. They can identify the leather, give you proper advice and recommend appropriate treatment.
If you have a case from John Barton, Jim Murnak or Jack Justis, send them a picture and they can tell you what to use, and maybe even remember when they made the case.