Dusk,
I try to get into RF while it's still light so I can see where everyone is.
Normal, 1 Controller approx 5-6 Monolith beside the bus, sometimes a couple of them coming up the hill, either them or Freedom.
I head down to the break in the fence to hunt the Controller,enter the woods looking for him and the 7-8 loner zombies, following the fence line till I reach the pipes(RPG guy pipes) If I haven't met the Controller yet this is where I'll find him.
take a detour up the road to the switch to... (I've forgotten where this switch leads to, sry) normaly 6-8 Monolith either just outside the compound and a few inside, kill them, need to be careful here as sometimes a couple of Loners spawn in.
leave the area and backtrack following the road up to AW/RF switch, a Controller is normally hanging around with the Monolith(4-5) at the road block, take them out and continue to the switch, few rodents and lesser mutes come through the switch and sometimes a Controller.
start out again heading down the road but instead of following it,head into the woods themselves, play hunt the loner zombies, (too early for the Controller) leave the woods by the hole in the fence where the dead eco guys are and head up to BS, take out Monolith going up the hill and about 7-8 inside the rail yard, head down the hill, Monolith are back at the Pripyat/RF switch, ignore them for now, head past the bus shelter and down the road, you should feel the Controllers aura coming from the woods but ignore him for now,go back to the compound (road to the right) Monolith are back, take them out, again watch out for the two Loners that spawn in.
walk down the road, get to the pipes again if you're lucky the loner zombies have come out of the woods along with the Controller, if not then go back into the woods and hunt them.
take them out, then it's time to take care of the Monolith and Controller up at the Pripyat/RF switch.
hang around the switch, I normally get inside the bus to wait for more Monolith(4-5) to either spawn in or come through from the Pripyat switch(2-3).
I can normally get two of these "sweeps" done before it starts getting light.
of course I haven't mentioned "Horror Times",Blow Outs, Chopper attacks and mute attacks that I also contend with.
this is all done at night.
once day breaks, I head back into Pripyat and it starts again.

so with the 3 sweeps of Pripyat and 2 sweeps of RF/BS I can average about 25 Controllers, give or take a few.
this would be one nights gaming for me, again depends on what/who I bump into.
Timing is important, because if you try and come into an area before everything respawns it really, really screws it up as the Controllers will start appearing in weird positions,you have to give them time, besides theres always lots of other things to kill to keep you interested

edit: also dont forget to change the re-spawn rate to Very Frequent