I have some experience with that. I have divided 25 liter tanks into two – so I have two 12,5 l sections. And I have divided a 54 liter tank into three – so now I have 3 sections of about 18 liters.
I can clearly say that the water is much better in the bigger tank. The water in my smaller single tanks of about 12 and 18 liters and in the 25 liter tank divided into two has almost the same parameters: pH around 4,3 and a conductivity of about 48 µS.
Same intervals of water changes – the water in the bigger divided tank of 54 liters has the same pH of about 4,3, but a conductivity of only 21 µS.
Deepin peat’s advice is right – and I have yet another reason for even keeping only the same species in these divided sections: The partitions are not tight, and they are not wanted to be tight – because of the advantage of the greater overall water volume. The water is desired to diffuse between the single sections. And I have experienced that also very young fry diffuse between the single sections. We don’t want to mingle fry of different species, don’t we? So I would not recommend to keep different species in neighbouring divisions of one large tank.
In my divided 54 liter tank I have my P. quindecim – eldest pair in the left section, younger pair in the right section – and their offspring in the middle.