Always just wondering, even though it's not in all the games after Gen 3, why do most of the Speedrunners choose the girl instead of the boy? I'm just curious of finding out why. But on some games they just choose the Boy.

Example: Let's go Pikachu/Eevee = Boy vs Sword/Shield = Girl

I think it save some seconds if the players choose the boy and not the girl, but prove me wrong of why that's not the case for some of the games.