“I’ve seen a lot of dubious-looking types roaming the countryside today.”

“I heard they were draining the English Channel so that England is forced to join up with France and be part of Europe again,” she said.

“We’d better get that dance in before it’s too late,” I agreed.

And my point is that to a large degree the future is unknown.  You probably don’t know what advertising your competitors will be doing, what new products they might be offering, or how the mood in schools will change.

But you can be sure that most of your competitors will be doing one thing: advertising occasionally.  Only a tiny minority of firms selling to schools advertise on a regular basis.  An even smaller number do it with that most effective of techniques: constantly changing adverts.

And yet, because of the endless changes in mood, policy, curricula, and finance it is hard to know when teachers will be particularly moved to buy x and not y.

So just as the dancers know it is important to keep dancing, so with advertising it is important to keep advertising.