[Someone]

No, it is not. I have not tried proving it, but I would think the winning strategy is not "to avoid detection", but to "make it as hard as possible to detect your smallest ships".

I tend to place the large ships as close together as rules allow, in order to leave as much freedom to place the smaller ships. Something like (if ships can lie along a border; periods are squares where no ship can lie):

    #####.####
    ..........
    ###.###..
    ........

[Someone]

Clarification: apparently, I tend to play a different game than what this text is about. The game I know forbids placing ships so that they touch (sometimes allowing corner touches). With those rules, finding a large ship can rule out lots of spaces from the search space. For example, a 5x1 ship has up to 16 bordering squares.