In a traditional IT development project there is a tendency for one person to write entire programs to implement certain functionality. A developer tends to own the code that she writes.

When you build a schedule you need to understand how to estimate duration. If everyone worked eight hours per day, and was 100% productive for all eight hours, you could easily calculate duration by taking the number of effort hours, divided by the number of resources. For instance, if an activity was estimated at 80 hours, and you have one person assigned, and he works eight hours per day, the duration would be (80 / 8) = 10 days. Likewise, if two people were assigned full time, the duration would be (80 / 2 / 8) = 5 days.