Drone or otherwise I think mix is always important. A parametric EQ is a great tool for shaping the overall sound (even in the master). In the best case, assuming your drone is made of multiple elements, you can EQ each part in isolation (once the master is muddy it can be hard to recover). Specifically you can cut frequencies that aren’t required for a given part: this leaves space for other parts so they can sit together in the mix together comfortably. Moreover my watchword in initial mix is always clarity: cut frequencies from parts to allow others to be heard.
EDIT: a few additional points around mix: I’ll focus on the most minimal mixing Vs including effects and other elements. I tend to do a technical mix, then an “artistic mix” as a second pass. For the technical mix, I usually find the busiest part of the track and loop it. I’ll start the mix in mono initially using only the levels to get things separated. I then use EQ to refine that separation (still in mono), then I move to stereo to pan things out from more separation. I’ll usually iterate on the levels and EQ a little in this context, but I’m always adjusting for clarity. This first pass should be a static mix, adequate for the whole track. With the initial technical mix in place, I then do the artistic mix. I tweak the mix to match my intention more. If the initial mix was really good then this will make things less clear; this is where I deliberately introduce imbalance and overlap to match the “artistic intent”; in other words you can make a technically worse mix of it matches your intent. This is also where I tend to add dynamic mix elements to support the overall concept.
