barmar, on 2016-March-20, 02:03, said:
As has already been pointed out, this is untrue in several jurisdictions. Consider that the player in question might have remembered that he ought to alert this natural 1♠ bid without remembering exactly why. I would advise an alert if, say, 1♠ included a weak jump overcall because 2♠ had been assigned an artificial meaning.
Regardless, I never have sympathy for assuming a bid is not natural just because it has been alerted. Say it goes 1NT-2♣-2♥-3NT, with 2♥ alerted because it shows 5 hearts. Opening leader, instead of asking, leads a heart, giving away the contract. Are you going to give him an adjustment? Of course not!