Hey Mike,
To be honest, your question is just to open ended without more information.
If you can give the brain trust around here some more information, it will help your cause.
As Amos Otis just asked, the variety (the genetics). That will play a big part.
But also, your setup, what lights your using, what nutrients, temp and humidity in your grow space, what type of plant training, ect...
Are the dense nugs you are getting the top colas?
One may be able to take two clones from the same mother and give them to two different growers and get two different density nugs from them, because their setups and methods of growing the same plant differ.
This is a long way of saying what Chip Green just said.
Hope this helps,
Cheers,
WillieP