I have my own answer to this question, but wondered what others think.
When I change the 1:1 in my top bar hives, all I do is remove the outer lid or cover, and then remove the 3-4 bars above the feeder jars to replace the syrup. Since the divider board separates the feeder from the brood nest when I replace the feeder I do not in any way disturb the brood nest and in fact do not even see it.
I would suggest that when I do this it does not significantly bother or set back the colony as a bar by bar inspection or manipulation would. Would you all agree?
I am asking to see if I should be overly concerned about how often I might be doing this and not negatively effecting the development of the colony.
Appreciate any thoughts!