As far as he was concerned, the one time it worked was worth it. And, yes, the siblings will expose one another for cheating. Kids can be incredibly clever, which is why they must be watched at all times. Now the problem is when there's collusion so that they don't expose one another ... or else they blackmail each other into keeping silent by threatening to expose some other misdeed. Ah, yes, the marvels of Original Sin.
My 10-year-old son tries to avoid showering by running the water while he just sits there on the closed toilet. Would have worked except that he'd come out looking and smelling just as dirty as when he went in. So now my wife touches his hair and smells him as he gets out. Smell will usually give him away. And he sat there as long as it would have taken just to do the job right ... so that it wasn't even about saving time, but about being lazy.
Oh, yes, he would flash that huge Cheshire grin of his with pie crumbs all over his face. And then it was off to the next conquest.
If he could not get the next piece of pie, then he would stay up, and when everyone else was asleep loudly snoring, he would tiptoe into the kitchen and have himself whatever he could find even if it met that there would be no food left to make the school lunches in the morning.
Please pray for him as he is among the lost. We do not know if he is dead or alive as we have lost all contact with him after his wife died.