Question about ssh-keygen -a rounds

[raf]

Hi,

man ssh-keygen says:

  -a rounds
     When saving a private key, this option specifies
     the number of KDF (key derivation function) rounds used.
     Higher numbers result in slower passphrase verification
     and increased resistance to brute-force password cracking
     (should the keys be stolen).

What constitutes "Higher" here? Is 100 high or is 100000 high?

What's the default number of rounds in the absence of the -a option?
Could the default value be added to the manpage?

cheers,
raf