>in either case, the bees will push towards 15% (more or less) drones in 
the hive...

Is there any real evidence of this?  Does the queen not have any tendency 
to lay any proportion of drone eggs?  Does a hive not tend to maintain a 
certain amount of drone brood or drone comb?  In other words, is the 
percentage of hatched out drones practically the only thing that matters?  
Are there not stages of development at which hives tend toward vastly 
different percentages?  I suspect your explanation is misleadingly 
simplistic.

Most to the point, interspersing empty frames into an established brood 
nest isn't natural and it leads to unnaturally high levels of drones/drone 
brood/drone comb/mites.  That's fine, if you want to raise drones/drone 
brood/mites, but it's not natural, and it's probably not good for the 
beekeeper (short or long term).

I'm not suggesting at all that you should be "constantly fighting" with 
your bees.  Obviously, using foundation avoids the fight.  But if you're 
not going to use foundation, I would suggest letting your nucs and swarms 
draw comb for you.  An expanding nuc will draw (more or less) 100% worker 
comb, as will a beginning swarm, which makes sense, because those are the 
kind of hives where brood nests would naturally be built out.

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