This is a common question and I hope you will find the User Guide useful:http://supportdocs.spacial.com/SAM+VIBE/SAM+VIBE+User+Guide.pdf
But in answer to your question, whatever is in the Queue will take priority and no Playblocks will play whilst there is anything in the queue. When scheduling a Playblock we recommend adding the 'Queue Loop Off' and 'Clear Queue' tasks before scheduling any Playblock. Once the Playblock event has been triggered, this Playblock will play repeatedly until something changes, e.g. a further scheduled event loads a different Playblock or by adding tracks to the queue.