Varga charts as being taught and propagated as the 30-degree independent chart need to be reassessed and reworked to something more acceptable and compliant to the classics.
You do not find even a single reference wherein it is suggested to allocate houses to the Varga charts rather they represent the degree-wise allocation of the planets and the lagna in different Varga or divisions this, in turn, provides us with the subtle influence of the lord of the sign where the planet is placed, for example, Moon is 10 degrees five minutes in Aries in Navamsa it will be placed in Cancer Navamsa. Hence, it is in its own Amsa thus, there is no specific outside influence in Drekana it is Leo's sign thus the subtle influence of the Sun as drekana placement lord.
Some people draw out a chart that is D81 and call it Sooksham Navamsa dividing 30 degrees by 81 we get 0.3703703703703704 since it's not divisible the solution is to go back into Navamsa and then reassess the Navamsa from Navamsa D9 XD9.
The D3xD3 can also be done but it will be different from your D9
Similarly, D24 can be drawn out as d2xd12,d4xd6, or d8 xd3 but its placement and result will be different from what the D24 produces.
