I just bought a Ox blood Chesterfield leather lounge. I want to look after the leather so it doesn't crack and go hard, and as I have never owned a leather lounge...
When we got our Gascoigne leather lounge about 25 years ago, I was told by Gascoigne not to put anything on it other than a damp cloth to get dust off. That is all it has ever had and it is as good as the day I got it.
We upgraded our upholstery in the van from fabric to leather, due to the ease of looking after. The product sample/recommended supplied was Shann Leather Cleaner for Leather Lounges and Shann Leather Conditioning Cream.
We wipe the leather over weekly with a mildly damp cloth, and according to the leather cleaner instruction, use the leather cleaner once or twice a year. The conditioner can be used every 3-4 months.