Grand Ma's "Feed the yeast" Fact or Fiction?

I recall my grandmother adding small amounts of confectioner's sugar to the flour while she was in the second or third cycle of kneading the dough.  Although it might sweeten the bread a bit I wonder if there was a different purpose.

Would not the addition of small amounts of sugar after the first kneading give the yeast a boost of energy with more food to ferment?

She did always seem to have her dough rise much more than mine.

Also, when she wanted to flavor the dough a bit, she would also knead in cinnamon or dry malt. She would not add these in during the original mix.