Hi,
for the purpose of a strategic process model, this already looks quite good!
A strategic process model is meant to display a complex process with 10 or fewer BPMN elements. It also relies on pools and lanes to display responsibilities, well done! It does not have to by semantically correct, thus, it can contain aspects that can not be automated. E.g., in your use case, it is not completely clear how department c knows when to start “Task c”. But this might be okay for a strategic process model, for example, if it is clear to your audience without further explanation.
For an operation process model (meant to be automated), this detail would need to be clarified. For operational models, it is not recommended to lanes. If you have a process that plays “ping-pong” between two departments and you want to display this in a single pool, that might be okay. In general, when working on these detailed operational process models, the departments get their own pools which helps describe their start and end events. (E.g., what exactly is the start event for department c? A message start event?).
From an aesthetical perspective, I did some adjustments to your process, see image.
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This kind of question would be very suitable for that program, so feel free to join.
Best regards
Till
