Analogies can be useful teachers. Seth Godin published this about Express and Local trains, which creates a perfect analogy to understand time span.

Express trains run less often, make fewer stops, and if they’re going where you’re going, get you there faster.
The local train is, of course, the opposite.
Some people hop on the first train that comes. A local in the hand is worth the extra time, they say, because you’re never quite sure when the express is going to get there.
On the other hand, there’s a cost to investing in the thing that pays off in the long run.
Now that you see that, you’re probably going to notice it in 100 areas of your life.

One of those hundred areas is time span.

Local trains (short time span) require very little thought, not much of a plan. The train (bus) picks a route and stops every place (enough) people want to stop. It uses the same track day after day.

Express trains (longer time span) requires more thought and much more planning.

• Which routes would benefit from express?
• What is the threshold criteria for an express?
• Which stops to skip? Which are served by a local?
• Which tracks to use? Which tracks to skip?
• How to evaluate the effectiveness of an express?
• What if something changes and the express is no longer effective? How do we know?

Think about your projects, your customer service, your web portals, product delivery, warranty programs, quality programs, research and development. What is your express train? What is your local?