Can someone help me understand trading tactics better

I am confused as for how trading tactics actually work, say for information short fall, i am trading to minimize the shortfall risk and cost? How does it work in real life and why is it good for small trades with high urgency while the other weighted tactics do not meet such demand?

With small trades there is less market impact and a lower chance of orders being delayed or pushed down in the order book. Its good for urgent trades because research has shown most implicit trading costs derive from slippage and/or opportunity costs. Costs are lower by being executed quickly. I took that from the curriculum, its not my research.