Organizations will over time establish some internal standards, of how Volt apps should be build, look like and integrate with other systems.
They could create a standard Volt template to create all Volt apps from, but it would be more flexible to have a kind of "element library" app authors can copy elements from into their apps.
Elements "libraryrized" most likely are (in my opinions) in no particular order are:
styles/themes/css with corresponding images and fonts,
(external) service definitions (e.g. for calling SAP REST APIs).
Optimally: Make those relationships a permanent inheritance, thus additions and corrections of library elements get inherited by other Volts apps using them.