Looks like it would just end up one tangled mess

 it would for sure

 Doesnt stop people using them though. Saw a guy at the south mole using one catching hezzas

What is the reason for a limit of 3 hooks / gangs per rig, is it simply to prevent people from catching alot at once or perhaps so you can't accidentally jag and injure fish ? Something i have wondered for a bit. 

When I first saw this, I thought with about 20 tiiiiiiny hooks using fluorocarbon instead of obvious red string, and a dough mix on the hooks and in the holder would be a productive way of mullet fishing. Just a thought :P 

 I think aslong as you play by the bag limits i dont see what the problem would be as fish would take the bait. Jagging is not allowed but if you see a school of mullet and put gang hooks on that wouldnt be excepted either. even though you are playing by the rules beside the jagging bit.

Those wasabi rigs come in 6 for catching scalies your meant to cut them in half but how many people actually do.?

 looks like the ones they use in america for blue fish eh except they have bit bigger skirts on. Look like something that could be effective just to reduce time catching bait.but not every one fishes for what they need :p

I have seen a similar thing used at E shed on scalies with all six hooks. The person who was using it was catching 4-5 every time he put in in the water.