I'm not playing at all right now, for several reasons. But...
Back in 1998, when I discovered Silent Hunter 1, couldn't decide which of the two starting ports (Pearl Harbor and Manila) to start from. Then I couldn't decide between S-boats and the Salmon/Sargo class, or between a Gato or Nautilus. I ended up running four separate careers, and more when the Australian bases opened up.
SH3 was easier at first, but Beery's Port mod (incorporated into GWX, NYGM and SH3 Commander) opened up the world, and then SH4 came along, and SH5. Once I have a computer that will run all the mods and games I want, I plan to start in August '39 with three careers, one each out of the available flotillas, then add in the same in SH4 U-Boats, then maybe SH5 as well. If and when I finally make it to 1942 I plan to include careers in SH4. My habit is to run a captain until he retires or dies, then replace him with a new one in that command starting the same month the old one ended. Heck, I might play AOD and SH1 as well. Ten, twelve simultaneous careers?
OCD much?