Jacks don't ambush, they just swim around looking for bait, sometimes they show up and sometimes they don't, or be a mile away without you knowing it. They can stick around for a while or be gone in a minute, you just never know with them. For me it's fish I don't target, I catch them when the opportunity is there. I don't fish live or cut bait, only artificial, that said when jacks are busting they will hit anything, my most used lures are a topwater or a mirrorlure twitchbait and you can never go wrong with a spoon or a bucktail. I believe the bucktail will improve your chances of hooking up with other species too, like a snook. Don't over think it, if they are around your gonna get one.