Your first goal is an MVP – minimum viable product [not Microsoft’s most valuable professional.] You define a few features and envision a few screens. Sure, without going into any details. And you go with scrum from the beginning. You’re agile, yeah, right!?
During the first sprints you come up with a simple architecture, supporting one or two features and one or two types of screens, just enough for you to be able to start the real development.
The next few sprints you’re working on similar features and improve the initial ones. For some time, everything is still fine.
Then a completely different type of screen or some very complex requirement details arise for either existing or for newly discussed features and they are not fully supported by your original software design.
You have now a lot of work already done and changing the design completely would require a lot of (logically acceptable, from the agile perspective) refactoring.
In theory, it’s indeed still fine: you shouldn’t prepare anything until it’s really needed. However, the redesign would now require at least two sprints to finish, and your customer is not going to “buy it.” Or even if they did, won’t cha wish
your girlfriend you had known about those important requirements beforehand, to incorporate them into your otherwise brilliant initial design?
But it’s too late at this point, so what are you going to do?
You [are forced to] find shortcuts and workarounds to solve the issues… and keep the client happy and the product still “on track.”
And yes, everything moves on. For another while. Until emergencies appear again. Until (eventually) everything becomes a mess. Be sure it will, either sooner or later.
Sprints are still green maybe, but the software is redder and redder.
Maybe you will finish the MVP before the deadline, but hey, could you still maintain that code for much longer without a full refresh afterwards? (Remember: v1 is not supposed to be the last one!)
Don’t do this. Don’t scrum without a reason. Waterfall instead whenever you feel it’s better! Sometimes details must be decided before you actually start coding anything!
Or everything can be a waste of time.