First of all my apologies if what I'm going to ask has already been answered somewhere else, I promise I've looked around and found no clear response or any explanation that matches the problem I'm facing here.
So, I'd like to understand once and for all, HOW the output of a mining drill is calculated based on the mine field properties and drill ones.
So far I understand that the drill will harvest ONE of the tiles underneath at a random pace, and then extract (some) quantity of ore of it.
The mistery comes here, imagine I've placed a drill over a field with 1000% yeld per tile more or less. His mining speed is 0.5, expected ressources says ~70/s. But i'm getting something more like less than 1 per second.
This is what I don't get. How to fully exploit these rich, dense, high yeld ressource fields to the fullest ?
In advance, thanks for any help

Cheers