Can't split load on multiple nodes. Why?

Please tell me, in the previous mention it was said that if there are more than 4 nodes on the /24 subnet (or 1IP address), then there is a problem, and as I understand it, it is better to take into account a larger number of catches in one subnet?
What is the rational limit?

The question is that just like 1 node - one disk, if you expand, you need to create a separate node, but I already have several of them.