[Tom Bunch]

It's one of the more challenging tasks we have to balance what should be visible in the interface with what should not. Certainly huge swaths of blank off-hours in the Gantt chart are not typically useful. That's why by default the Gantt chart displays the project's on-hours. If you want so see a different set of hours on the Gantt chart and Timeline view, go to View -> Calendar View and modify the "Normal Work Week for Project".

Of course, this is going to modify the working hours for all resources that do not have a custom schedule, so you'll need to set up resource work weeks as well. You can customize them in bulk by grouping them. Select all resources that should share the same basic schedule, in the main menu, Structure -> Group, select the group, and modify its schedule. The resources in the group will inherit the group schedule and can also be individually modified.

-Tom