Can we increase the Parallelism for Non-Keyed Windows by setParallelism?

From the article below we know the parallelism is 1 for non-keyed streams, so can we increase the parallelism by setParallelism ? "In case of non-keyed streams, your original stream will not be split into multiple logical streams and all the windowing logic will be performed by a single task, i.e. with parallelism of 1."

https://ci.apache.org/projects/flink/flink-docs-release-1.3/dev/windows.html#keyed-vs-non-keyed-windows