Should they allow lower ranked players to go on playing for so long? Won't a coin toss be better?

Regardless of who the players are in terms of ability, I'm of the opinion that beyond a certain point, the same rules as with a tie break should come in. Say if the stalemate gets to 12 -12. Leaving it to the 'last man/woman standing' is pointless (no pun intended).

Really? You would have hated the Isner-Mahut match from Wimbledon a few years ago. That one lasted three days.