The Scrum Guide is clear in stating that if you implement some of the parts of Scrum, you may see benefits. However, it also states that although implementing only parts of Scrum is possible, the result is not Scrum. In other words, Scrum works best when implemented in its entirety. That means employing the only formula you will need in Scrum (3+5+3) i.e. 3 roles, 5 events, and 3 artifacts.
Roles
1- Scrum Master
2- Product Owner
3- Developer
Events
1- Sprint Planning
2- Daily Scrum
3- Sprint Review
4- Sprint Retrospective
5- The Sprint
Artifacts
1- Product Backlog
2- Sprint Backlog
3- The Product Increment
But what about product backlog refinement? The process of product backlog refinement is considered an ongoing activity in Scrum, not an event. This is because the activity is expected to happen frequently and should not be confined to any one time in the Sprint. This, however, tends to be an academic answer, and many teams schedule product backlog refinement sessions. Thus, they treat it as an event. I am in favor of this practice if it is supplemented by ongoing Product Owner activity that refines on a daily basis.
Just like product backlog refinement, there are other activities and elements that will aid a successful Scrum team. But your first step in avoiding the pitfalls of an ineffective Scrum team is to employ 3+5+3.
Happy Scrumming!
