The readers preparing for various certification exams are a constant source of amazing details, including this one:
I have configured ip ssh timeout 60 and exec-timeout 5 on VTY lines. Preferred input connection is ssh. How much time can I be idle?
According to the IOS documentation, the ip ssh timeout detects the problems in SSH negotiation phase (including user authentication) and the exec-timeout detects user inactivity after the user has logged in.
Do not set ip ssh timeout to a very low value or you won’t be able to type your password before the router disconnects the session.