In kenaflow workflows are executed in parallel. You configure how much can run this way at the same time. It depends on the capabilities of the server and of the performance and capabilities of your SharePoint farm because the farm has to handle all the client requests made by kenaflow.
All workflows are queued for execution. Most workflows have a setting called "TBE" (=Time Between Execution) which specifies the amount of time between to starts of the same workflow.
When a workflow should run again because of its TBE and the last start time it is not guaranteed that it is executed immediatemy because other workflows could run at that time and it's possible that others are also waiting in the queue with an higher position in it.
BUT you can use "Workflow Priority" to move workflows up in the queue.
The priority is a integer value in the
_wfconfig.ps1 workflow config file.
Each workflow has priority 0 (zero) by default.
You can specify any integer value you like.
The priority engine will figure out what to do. If an execution lane (that's how we call one parallel execution opportunity) is free for the next workflow the priority engine compares all waiting workflows with their priority settings, TBE, last start time and other factores. It decides what workflows will run next on the free execution lane.
There is a way to simulate the priorty engine to see how workflow execution is affected by it.
(Will be written later.)