Over the last decade or so I found that more and more sotware developers struggle with scrum.
So if I change Scrum (my process) - is it still Scrum (the approach)?
One thing that puzzles a lot of people is the fact that Scrum has to be amended past the 16 pages of it's official definition. The definition itself says so.
Yet on the other hand the battle cry of a huge body of people who call themselves agile professionals is "You are doing Scrum-But."
So where does that leave the teams? Torn between "Inspect and Adapt" "Responding to Change" and "Don't do Scrum-But."
Is it Scrum-But, Scrum-And or something completely different?
Of course it is possible to philosophize about this question a lot, but for the experienced software developer it should be easy to grasp. If you have a background in "clean-code" (as Uncle Bob calls it) or are familiar with the SOLID principles for other reasons the following picture says "it all": (metaphorically speaking)
If you look at it as a programming construct Scrum is an abstract class – it defines behavior, data, interactions etc. but some parts are just defined via template methods and stuff has to specified for the concrete implementation.
And for the concrete implementation it makes sense to apply the same rules that make sense when designing object oriented software.
So your subclass should only interact at the designated points without meddling with the innards of the superclass (OCP Open Close Principle). And your implementation should be usable wherever the super-type is usable (LSP Liskov Substitution Principle)
I'm not sure about the other aspects of SOLID, but transferring this thinking for the LSP and the OCP to Scrum implementation – together with the idea that Scrum is an AbstractSuperClass – helps to answer the question whether we're facing a scrum-but or not.