It depends on how many shots you're firing & how many fish have already been fired. Taking the U.S. example: if you fire 3 at one target, you can shift targets as fast as it takes to move the 'scope, enter the data in 10-15sec (or less, depending how big the change is: is the range & bearing very similar?), & shoot #4 in under 30sec from #3. (The delay between shots, sometimes as low as 5sec, which varied by skipper, was to prevent countermining, ''i.e''. having the following shots set off by the explosion of the first.) If you had to go from bow to stern tubes, then it's a question of how fast you can swing the boat, which is a function of her turning circle (U-boats turned pretty handily, but it's still above 30sec, even presuming you don't have to come full about; how much, I have no idea) & how much noise you can make.