Which Sun Do Tzu Orbit?

[Narwan]

I was nodding along in agreement until I hit this one. I'm curious as to what isn't useful intelligence.

Quite literally what it says; intelligence you can't use. Recon and intelligence gathering isn't a goal, it's a means. The point is to act upon the info. If you can't act upon something, often you risked the unit gathering the intel for nothing. Timing is essential. You have to know when to pop your head up for a quick look around and when not to. Gathering useful intel means your intelligence gathering has to be integrated into your plan of action as a whole.
Which is also why I completely disagree with your point of a trade-off. Recon isn't about knowing everything all of the time, it's about knowing the right thing at the right time. And that wins games.