The coarseness of the grind and the extraction time are inextricably linked. The finer a coffee is ground, the more surface area there is. Conversely, the larger the grind, the smaller the surface area.
Let’s consider the two ends of the extreme. If we grind coffee as fine as talcum powder we have maximised the surface area available for extraction. Therefore, we can very quickly extract the target compounds – but perhaps too quickly for some people’s tastes.
Turkish coffee is very finely ground and boiled. This produces a coffee which is very strong and bitter and because of the fineness of the grind often contains a lot of suspended solids (muddy). The finely ground material may block filters too, causing the extraction to go on for too long – or not allow the water to pass through at all.