If you want a commit to happen then you need to use the "writenow" option when doing obj-save. Otherwise, it is added to the deferred list and committed say when you submit an assignment.

Screen refresh should never be committing data unless the refresh activity is explicitly doing it.

I think refresh activity will be hard to maintain that's why we do deffered-save or commit on submit of an assignment

Can you also please confirm if execution of an activity through a Utility shape will result in a DB commit or not?

It will result in DB commit only if you have obj-save with write-now option in the activity