Regular PGP updates dramatically increases OPSEC by confounding decryption. 300 messages with 5, 10, or 50 different PGP keys, all with high levels of encryption (>2kbit). If you don't change your PGP at least every 6 months, then you're giving your adversaries a permanent solution to your cipher. Besides, when you delete an old key, it's gone from your computer forever!
Stagnant encryption sinks ships. Don't get stuck in the doldrums!
I don't understand this ( I don't have the technical knowledge). How could using the same PGP key for a long time give "adversaries" a way to decrypt messages and such?
I am honestly asking, not questioning, doubting, etc.