That will depend where you hit it, also the fight & strength in the different species of fish. Our kingfish seem to pull twice as hard as small marlin of comparable size & dogtooth tuna pull twice as hard as an equilivent size kingfish. Some species fight clean & some head straight into the reef. Generally, you should be able to have a 10kg fish in your hands in a few minutes at the most. The longest I have played a fish was a large tuna & that may have been 45 mins, spear shooting down through centre of back. The faster you can get them in your arms the better your chances of landing them, this should be a consideration when selecting gear, dont just go for the minimum you think is necessary. As you are from Australia also, I will just stress the importance of never second shooting one of your mates fish, even if he is having difficulty with it. It is considered an insult, & the fish can never be considered as a capture or trophy if he does land it. The only form of assistance which is allowed or acceptable, is to hand your mate an unloaded gun without a rig line or float attached so they can second spear it themselves. This has been part of our rules & culture for over 60 years, & too often we see young blokes trying to claim catches for assisted fish. These fish would not even be photographed or discussed in my day.