I find the ones without shells and head a bit quicker to rig (okay maybe a second quicker), when they have a head I normally rip it off and throw it away.
This is how I rig mine, sometimes they are a bit long so I would tear 5mm or so off the thick end. Then I thread the prawn along the curve of the hook like the image shows… then I use excessive amounts of bait elastic in both directions to hold it on very tight… Can last several hours in the surf if nothing feeding, although I normally replace with a fresh baits every half hour or so if nothing happening. I use 4/0 Owner Circle hooks.
If I am using a flasher rig, then I actually wrap the flash down with the elastic and get it to merge into the prawn.