On this blog https://blog.josefsson.org/2014/06/23/offline-gnupg-master-key-and-subkeys-on-yubikey-neo-smartcard/ there is a following sentence
Generate master key
Below I will use a 3744 bit RSA key, where the key size is selected based on the assumption that people will focus efforts to crack RSA keys on the usual power-of-two key sizes.
But that leaves me to wonder: do unusual key sizes really pose a disadvantage to a potential attacker? After all, couldn't he just get a key size from a public key?