I do on occasion walleye fishing. It's a pretty short leader 14-16" but its not line to line, it's attached to my braid mainline by a quality barrel swivel.
It's definitely not needed though. I still prefer running just straight braid.
One thing you'll get with fluoro is more sensitivity(as compared to mono), because of its low stretch. Alot of people will also say it adds abrasion resistance, but I don't find that to be the case until you get up to really high breaking strengths, like 60lb+.
You'll also hear that it sinks moreso then mono or braid, which it does. But it's a very, very small amount if you run your own comparisons to see.
So why do I have it on one rod you might ask? No real good reason actually, as a matter of fact I think I'll go take it off right now. Cause at lighter tests, no way fluoro is more abrasion resistant then braid.