From what can be gleaned from the Campfire, most members sight-in their hunting rifles by putting up a paper target 100 yards from a benchrest, then shooting the rifle and adjusting the scope until the rifle puts groups where they want them to go. However, there are plenty of variations, and over the decades I've seen quite a few, due to visiting a lot of ranges and hunting camps.
FWIW I'll usually sight in at 100 metres (ranges here are generally denominated in metres rather than yards) , but with a hunting rifle while I use a rest I am actually holding the rifle in my hands, weak hand holding the fore-end. I might do this over a benchrest or over some other rest, such as my daypack.. Holding the rifle like this is how I'll take the longer/more critical shots, so I want the POI to reflect that hold, rather than, say, sitting the rifle directly on the benchrest, and perhaps letting it recoil freely.
With a new rifle or new scope I will typically start at 50 m after boresighting. With a new rifle or load I also like to see how it goes at longer distances than 100 too, but once I have that sorted then confirmation of zero is usually just at 100.
I like to check zero before each trip. Part of this is confirming everything's lined up, part of it is having a couple of foulers down the bore before the shots that are to count, and part of it is just practice. I don't begrudge the few rounds it takes, and if I'm going to go bush for a few days I like to be confident that the rifle's on the button. Even just up on the family farm I'd check zero if I haven't shot that rifle for a while.
I've been on a few hunts with guides, and it has been my experience that they like to see you zero - more to see how close they are going to have to get you than anything else I suspect. They always seem to be relieved to see that a bloke can put them all into a nice tight cluster from whatever improvised rest they give you.
