The ring shot will always give you one elf ring, as has been mentioned. That said, if you take the time to look and see which other shots are lit for an elf ring you can make a pros/cons decision. Is it a shot you are good at? Is it easily comboed with another shot? If yes, go after it. After you hit the elf ring shot, all of the others will blink for a combo and you can immediately earn another. If not, bang the ring again. I find it's one of the safer shots in the game (assuming you aren't playing a machine that likes to give you spinner rejects).
Also: once you light all of the modes, the ring shot will no longer give you an elf ring. You've got to pay attention to what's lit once you hit that stage in order to light the ring for TABA.