It depends on the job. Sometimes it's the point in a job where you gotta know how to get in and out of a secured place to get someone, or something, out with you. In a team, I usually act as the Inside Man, that way I can get other teammates out if a con goes wrong.

[At least someone's accepted that it's just a name and nothing important he's lied about.]

I can actually handle myself. It's the paranoia, for many different reasons, that it's important to buy time to plan by going around with an alias. If someone showed up and asked for me, those that I know wouldn't be able to show they had a connection to me. That means it takes longer for the enemy to realize I'm around, and they don't know there's anyone connected to me to use as bait.