What would a commercial brewery do here? As far as i believe once it hits the gravity required they drop the yeast out of suspension straight away.
Am i correct?
Kind of.
First, congratulations on a speedy and apparently healthy fermentation that hit your target gravity. Great job! this means that you hit the perfect apex of pitching rate, oxygenation, gravity and fermentability.
I expect primary ale fermentation to take about 70 hours. Pretty much everything is still in suspension at that point, which is what I want, but the beer still has a half point of alcohol it'll produce. The temperature is held for another 6 to 9 days (depends on alcohol content), until the beer passes acetaldehyde and diacetyl tests and doesn't smell "raw." At that point, the trub has collected and is dropped, along with spent yeast (the thickest portion), the beer is crashed about 10 degrees and that will precipitate what I'll harvest. I get about a gallon (3 liters) per barrel (or hectoliter) for repitching.
I've discussed fermentation with Scottish distillers, who are fascinated at how long brewers will let beer sit. The simple fact is that beer yeast isn't finished just because it doesn't look busy.