I have an issue regarding the association between two of my use cases in a use case diagram.
The first use case is ‘Report laptop fault’ and the second use case is ‘Repair laptop fault’. One actor reports the fault to another actor, and that second actor then repairs it.
I have made a connection between the two use cases with an ‘extends’ relationship but now I’m second guessing myself. The faulty laptop could be put to one side and it could be some time before it is actually repaired (there is a prioritised list of multiple faulty laptops).
Does an extended use case have to be completed at the same time as the first use case or can there be a significant time gap between them?
(On a unrelated note, and this will reveal just how much of a beginner I am, is an extension from one use case to another acceptable when the two use cases have different actors?)
Thank you for your time,