User blog comment:Hayashi H/Advanced Equipment Guide/@comment-76.218.105.96-20151030035225/@comment-24930367-20151030042031

About that luck cap, there is a post that suggested the cap might be higher (60 or so for torpedo, 70 or so for gun-torp, 55 or so for gun).

And for the second...my take on this one is because their base stats (well, torpedo) are high enough to make their night double-tap strong, and double-tap is more reliable than cut-in. And since they are already strong enough even without luck modernisation, might want to boost other ships instead.