Do you just keep getting new objectives?

[Spraug]

Originally Posted by TorpX

Yes, but I think it is done on a probability basis. By that I mean, you can get the patrol at your discretion after one or two objectives, you don't necessarily need to have a bunch.

Indeed. I got a "patrol at your discretion" during my third patrol immediately after a 36h patrol of the Molucca Strait. And I got the discretion thing five times in a row.
Really amazing: we were trying to hold Java and they didn't have any orders for me! No wonder we couldn't hold the line.
Historically and logically the obvious next step of Japan was Timor, so I sat in the Timor Strait entrance for two weeks attacking two convoys when I was suddenly overrun by a Japanese Task Force (the one attacking the Christmas Isles and Java from the South) that I had not anticipated. I came back up to periscope depth South of the Southern of the two lines, dove again under a Mogami-class and a Kuma-class cruiser and just managed to get off torpedoes at the last fleet carrier. I had been plagued by VERY bad torpedoes the whole patrol (two ships only out of two badly guarded convoys) but this time we got lucky and Japan will have to attack Midway without Akagi (or Kaga)!