Trees need light on all sides to stay healthy. If they are not turned regularly the branches on the shady side get weak. In extreme cases all the back branches (usually it is the back against the wall) die.Question: turning the tree??? To evenly get sun all the way around? All year round? Never done that with my smaller ones, should I?
You don't need to take my word for it. Have a really close look at trees that have been growing in one position and you will probably be able to see some slight differences in health and vitality of the branches on the shadier side.
I try to remember to turn my bonsai 180 deg every week or 2. Won't matter so much in the winter when deciduous have no leaves and even evergreens are growing so slowly it probably won't affect them much but it is good to get into a routine.