Delay in being banned?

Hey,
My friend recently was banned for alching from 70-90 on his main.
Weird thing was, that he had not botted in over 3 weeks when he was banned.
Why the delay?

 

There are some many people that play the game, and so many people that auto that they probably have thousands of auto reports to look through. Would most likely take a couple weeks for them to look through them all. My friends just started autoing about 2 weeks ago and just got there 10 day bans. =/ I'm the only one out of my friends whos main hasnt gotten ban yet.

 

Hmmm....gotcha