VoU only described the classic concept of a GP Farm, having lots of

, working Specialists. There are also the

heavy GP-Farms that have lots of Forrests that can be chopped and that have Wonders, and there is the very late game GP Farm with National Park.
In my games I usually play with multiple GP Farms, in my Current game I had up to 5 or 6, but the main thing is, that they aren't used as GP Farms all the time, but only in Golden Ages because of the 100% bonus to

. Switch to CS + Pacifism and turn every city that has some Wonders and some

into a GP Farm and create twice as many GPs as you'd have otherwise.
Example:
First GP Farm: Capital, has Cottages +

, is a holy City, gets OX + WS, but in a GA it hires Prophets, Wonders, Oracle, Buildings, a Temple and a Shrine.
2nd GP Farm: GA-Farm, has MoM, sometimes SoZ, sometimes Parthenon, normally a city with lots of trees as those all have to be chopped out. Gets TM later and creates GAs only to start GAs
3rd GP Farm: GM Farm, gets GLH + Colossus, runs Merchants during the GA which are sent on Trademissions after that.
4th GP Farm: "Real" GP Farm, lots of

, working about 10 Scientists during the GA + having TGL sometimes.
So be creative, sometimes the best GP Farms are

heavy and don't have that much

, sometimes one can use hybrid GP Farms that run Cottages in normal times (and grow) and work Specialists during GAs. And maybe try to sort by Wonders, it's very unpleasent if you needed that GS but built the Parthenon in that city and got a GA with 1% chance.