I flowchart by hand when I run into some logic that is kinda tough to write out without the entire flow of it designed before hand.

I never flow chart and entire application, just small parts where I need it.

For example I wrote an application that is a paid subscription app, and when you start it up, it checks the subscription, and if they are current it does certain things like check for updates and download them, and if they arent current it does other things like prompt them to pay right there via the web, and then the logic has to backtrack after they pay to now download their updates, etc... that is kinda oversimplifying the entire process, but you get the idea.

I was getting kind of lost in all the logic, so I charted it out on paper, and got it finished much faster.

It helps you to see any potential pitfalls in the logic, and also makes you visually see on 1 piece of paper that all code routes lead to the correct outcome.