When to not do Scrum
If your work is perfectly plannable and predictable: don’t do Scrum.
If you do not want empowered teams: don’t do Scrum.
If you don’t want to disrupt your organization or upheave your organizational structure to empower teams: don’t do Scrum.
If you want an exhaustive set of rules to follow and do not want to figure out what works for your context: don’t do Scrum
If you don’t trust your people: don’t do Scrum.
Scrum is finicky.
At the core of Scrum are empowered teams that are trusted to make decisions and figure out their own way of working. This is often wholly incompatible with the prevalent mindset, existing way of working, and current structure of many organizations.
If you don’t have the right conditions to make Scrum work and don’t want to accommodate the necessary changes for it to shine, then don’t do Scrum.
You will just be constantly bumping your head into a wall.
Unless you are willing to break down those walls, don’t do Scrum.