Keeping S&F's on same side

I'm just getting into sourdough baking, and I've been using the stretch and fold technique during bulk fermentation for my first couple of loaves.  

Does it matter if all the S&F's are done on the same side of the dough?  For instance, after I do a set of S&F's, I flip the dough in the bowl, and round it out.  That way I'm rounding out the side I was building tension on.  Right before my next set of S&F's, should I flip the smooth side over before my next S&F's?  Because otherwise I would be building tension on the opposite side of my first set.

I'm also curious if building tension on one side is even important during bulk fermentation, or if these folds are purely meant to build strength within the dough.