dfscott,
Thread may be old, but if you are using SH3, it is still useful.
As far as what is realistic or useful, that is a personal choice. I find that all campaign scenarios vastly under report the close ship traffic near land and busy ports, but are very good for task forces and convoys.
My personal style is to markedly increase contacts of ships only if I plan to patrol near shore, especially if around the Caribbean or near England. If I plan to patrol in the open ocean, I leave the campaign.RND file as the original for the Major mod I am using.
If I am testing, I crank up all contacts.

Ok, thanks for the info. I was finding that when I chose the 7th Flotilla, the early career missions (i.e., late 1939), had hardly any targets at all, so I was trying to "spice things up" a bit at the cost of some historical realism.

Edit: Never mind, found another thread about this (http://www.subsim.com/radioroom/showthread.php?t=166252) .I forgot that the war hasn't started yet!