If you tightly wrap three or four layers of wood-glue soaked cloth around the break, along with gluing it normally, it is almost guaranteed not to break in that spot again.
Problem with that is on the knuckle I'm flying 98% of my breaks have occurred at a screw hole so they're under the knuckle plates. So adding any extra thickness to the boom won't fly.
I tend to only use the re-glued booms as temporary solutions while I wait on paint to dry on new booms or just don't have the time to make new booms. I've never had one break in flight or be the cause of a crash. But once they're reglued (especially around the screw holes) they don't tend to last through more than one or maybe two crashes.
And in a way it's kind of nice because it makes me fly a bit more carefully since I know I'll be looking at a 15 minute+ repair if I crash and because when I do crash it gives a nice fuse that seems to protect anything else from breaking. Probably saved me almost $0.10 in zip ties already! The only real down side is when the boom breaks instead of a motor coming off or a prop breaking it also usually damaged my LED strip. I haven't mentioned it in my build/blog thread but my LED strips are now really hacked up. I've had to add jumpers on them to bridge broken sections, scavenge resistors from sections with smashed LED's to replace resistors that have been knocked off or smashed on sections that still have good LED's and the reverse of that too. All because I'm so stupid cheap and because of that my quad is so cheap I just don't see much cause to take it easy and avoid crashes with it. At least not crashes that only put the quad itself in danger.