Utterly pointless.
The only thing you may achieve is a longer plug change interval, but given that since the removal of lead from fuel plugs last pretty much forever even that is a bit of a furphy when you do the sums.
With multi electrode or surface discharge type plugs you don't get multiple sparks, you still only get one, it just takes the path of least resistance so whichever electrode is least filthy? That's where the spark will jump to. Once that electrode becomes a bit contaminated or damaged the spark will choose whichever other one has the next least resistance etc.......
