this depend on the tournament. those who don’t support the eight button layout don’t support this think. thoso who do support this. (in six layer layout you have to put the other 2 key on no funcion and if the opponent suspect you are using select or other buttons you might be disquilified)
for what i know it’s like this only in europe. most mayor US tournament allow 8 button and in Japan it’s a mix of the two sistems but usually they play on the arcade so there’s not this problem