One thing that no one seems to address when doing sugar shakes is the stress it puts on the bees. Opening up the hive and completely dowsing them in powder seems pretty harsh to me, especially doing it on a weekly basis. It has to add to their stress level. Also if you are in a heavy SHB area, every time you open the hive, the SHB get the chance to distribute their eggs, once again increasing the stress level on the colony. My experience has been the less intrusive you are on a hive the stronger/healthier they are. Obviously if they are susceptible to varroa, and you aren't willing to weed out these hives, then some treatment is needed, but I'm not sure sugar shakes are as non-harming to the bees as proponents want you to believe.