I wanted to know about that too. Someone mentioned in another post that if you sign in via a different IP, then GMAIL requires another phone verification to actually log into the account. Is this true? If I don't have to verify every account then I'm interested as well for some.
Yes, If you login with another IP or use VPN Gmail will ask you to verify the account with the phone number you'd entered earlier while registering.
Yes on top of that there is always security risk. Anyone who has that number which was used to verify that email can anytime claim that his email was hacked and then Gmail would simply lock the email address and give it back to it's right full owner, which in this case would be the member who has the Phone number which was used to get it verified.
So in the end it's not worth it to have someone else verify your accounts (whatever accounts that maybe) because they can be easily claimed back by the phone verifier.
