You can try writing a simple spreadsheet with a =RANDBETWEEN(1,3) formula in a cell, then copy/paste the same formula to as many cells as you like, perhaps as many grids as the area you’re speaking of, then select an empty cell and press Del key and note the pattern of this area generated by the RNG each time you press delete.
You can colour-code the cells with Conditional Formatting so that 1 is green (forest), 2 is purple (swamp), and 3 is yellow (desert; or whatever colours you want) for better visualisation.
At any rate, I’m not here to fight. I’m just laying out the things as it is, and I’m not saying that I agree or disagree, unless I mentioned it specifically. I did make a suggestion in another’s topic, among the countless ones like yours, but I don’t expect things to change any time soon.
Anyways, please try out the spreadsheet scenario I suggested above. Make it a 10x10 grid so that you can see the bigger picture, then imagine your home grid is in one of them cells, and see how the RNG plays out. Iterate through a hundred times at least and count how many times the habitat pattern was “not to your favour”.
RNG doesn’t care about individual situations, unless there are condition logics written specifically for it, which makes it not exactly RNG anymore. But they did not write any logics for it because it has to be fair to everyone regardless of their situation. That’s just how it is.