When does a patrol end?

[VonHesse]

In a nutshell; your patrol is over whenever you want it to be. Stop sending status reports and head home.

Technically, you could do just one patrol for the entire war. The only time you will get orderd to return to base is when you drop below 10% of your fuel or torpedo load.

I personally like to patrol without refitting. Patrols for me generally last 30 to 40 days, accomplishing 2 or 3 objectives.