I used to do it all the time on r/b/y and g/s/c because I thought it worked. After having found out it doesn't work, I still do it out of habit.
It actually DOES in Gen 1 (and maybe Gen 2?), surprisingly enough.
button presses advance the RNG by a certain amount or something, which if you're using tool assisted games is excellent as it can guarantee you a capture.
This is obviously next to useless for people who DON'T use TAS runs, but hey!
That said, I practically started the down and B rumour in my school when I was a kid. --- Bullet Hell fan, Cave and Touhou lover. <3 Patchouli Knowledge. Playing: DeathSmiles, Fire Emblem 8, Rune Factory 3, Digimon World Dawn, Tales of Vesperia