Chris,
This is just an open opinion from what I have experienced, of which I will be happily corrected so I too can learn....
It does depend on the location fished. Barra do fight harder (IMO) when using heavier drag, but this is required in some places. Those places/structure that require such, are often places that I will "ëncourage" a fish to jump to keep them out of submerged snags (IMO). Then you need to back of to next to no drag (free spool) to get around obstacles. You really need to judge each scenario as it plays before you. Open areas do not need the same drag setting, but then you have the worry of abrasion on the leader. I wait for a jump or see what the fish does (you can tell where they are hooked from the run a lot of the times) and see where the fish is hooked before I back of sometimes. Like I said, it can vary (again IMO) but thats's what fishing is all about, adjusting to the current situation as no two days are alike
Hope this adds a little piece to the massive puzzle of impoundment barra fishing
Cheers
Matt
All just from some of my