I did some testing a couple of years ago just to satisfy my curiosity and I found that even just gluing scales to tang without drilling the scales at all provided a pretty good adhesion. It took some serious whacking with a hammer to get the scales to budge. I also tested the "drill into the wood to create an epoxy pins" thing and this held just as good, can't say better though.
The issue is shear force seen as being the #1 enemy but you should also include the prep work (fit up, sand up, clean up) & epoxy type as being factors as well.
If the knife is for your own use and you know that you'll not be whacking the hell out of it then aside from dropping it on the floor you'll probably be OK. If it's for someone else then you'll want to pin where you can.