Screenflow is basically designed to be processed by a single person and routing is configured at the start shape only (by default, "Current operator"). Unlike Standard flow, each step would use that routing and you can't configure it for each shape.
However, if the person who initiated the Screenflow is absent (let's call this person user A), some other person (user B) may want to perform the rest of steps on behalf. As long as user B has WorkMgr4 role, he can open other's assignment and submit it.
By default, when user B clicks "Continue" button, Confirm harness is displayed instead of showing the subsequent screen continuously with Perform harness. This is because system tries to "route" it to different person, although it is still in the middle of the steps.
Some customer may want the system to behave that whoever clicks "Continue" button sees next screen seamlessly. I think this requirement is valid, and there are a couple of approaches to achieve this. The simplest way I am sharing in this post is to tweak "PerformCriteria", without actually changing the ownership of this assignment. PerformCriteria is an out-of-the-box logic to determine whether to put the next assignment up into perform mode. It is "Available" and okay to override it although you want to be a bit careful because this is a pretty generic rule and gets evaluated every time "Add" or "FinishAssignment" is called.
To achieve above requirement, you can do Save As to your ruleset and add below condition:
if .pxFormName = "TabbedScreenFlow7" then return true
"PerformCriteria" rule is located at not only "Assign-Worklist" but also "Assign-Workbasket" (and "Assign-"). You can configure it as needed.