In my opinion, in Scrum, one of the less talked roles is the Product Owner. In many organizations, the role is even in a completely different department with a completely different hierarchy than the development team and the scrum master.
So it’s not that uncommon to hear that this role can be a part-time one. What do they even do? Right? Just writing stories in Jira and bothering the team with questions about when a story will be done. Anyone can do that in the morning and get the rest of the day free.
OK. That’s not just what PO’s do. They are responsible for the whole value the team produces, and that is hard work.
They need to be able to find new features and new value for the team to deliver. Refine whatever is already there and prioritize the work for the best outcome possible. That cannot be done in only half a day. Well, it can, if you want to do a half-assed job.
Remember one of the principles.
Business people and developers must work together daily throughout the projectagilemanifesto.org
There are no part-time roles in a Team. Everyone needs to be available to help the team move forward, whenever its needed (during work hours of course).