Being where the conversation begins is the smartest way to advertise in terms of striking the iron while its hot per say. Your target audiences first exposure to your brand would be most effective at a time when there is intent to purchase or use your service.
It is about being one step ahead a knowing your audience well enough to know where they first should experience your brand/service.
Another example could be that typically conversations about the TV series watched the night previous is discussed with work friends/colleagues the next morning. What do most people pick on their way to work? A takeaway coffee. Would an ad placement on a takeaway cup would help evoke the conversation and attract more fans to the show?
Where is your target audience talking? Be where the conversation relevant to your business begins. Speak to your audience directly by being there at the right moment.
Food for thought…