I have one hive with a super a little more than half way drawn and filled (at least a week ago that is where it was).
When should I stick the second one on? Is it like brood boxes with the 70-80% rule, or sooner? Also, should the new box go below the drawn box. BTW, I am using a queen exluder even though I know most here don't like them.
The rule i use is 80-90% full, which equates out to about 8 frames full and working on the last 2. I hate excluders and use them only in very limited situations such as retaining a queen that has a prediliction towards absconding as might happen in a feral hive removed from a wall.
The bees have to literally squeeze themselves through between the bars of the excluder and many hives will go into a swarm mode rather than work through one. If the queen goes up into the supers above the brood chamber put the frames down when you harvest and use the bee escape.
A very good arguement for using only 1 size of box--4 shallows is a bigger broodchamber than 2 deeps but there is no worry about which frame goes where.