Most airliners have 3 or 4 shock bodies to reduce wave drag. But why can't there be more anti-shock bodies per wing?
There is no reason to limit the number of anti-shock bodies to 3 or 4. In most modern aircraft, the anti-shock bodies are the flap track fairings which usually house the flap mechanisms.
As such, their number is determined by among other things, the wingspan, the size of control surfaces and the number of actuators required for their actuation etc. This usually limits their number to around 4 due to weight and other considerations.
However, there is no reason there should only be 3 or 4 of them. For example, the Antonov An-225 Mriya has a whole lot of them.
There can be, as aeroalias already demonstrated.
However, it would not be better.
Transsonic flow behaves strangely. It cares more about the total cross-section than its distribution. So for the wave-drag reduction it does not matter much whether there are two larger or many smaller anti-shock bodies.
However more anti-shock bodies with the same total cross-section have more surface area and higher surface area causes more friction drag. So more anti-shock is not advantageous.