I don't know why it would be a rule but the one time I tried it, I got absolutely rekt and never did it again. May have been because I put ALL my ships in one

I don't know why it would be a rule but the one time I tried it, I got absolutely rekt and never did it again. May have been because I put ALL my ships in one big blob, but typically people will fire at adjacent hits until they don't get any, so I think it's a terrible strategy anyway.