def _get_nomap_split_targets(analysis, is_cwl):
    """Chromosome splitting logic based on run type.

    RNA-seq -- aim for smaller chunks (half chromosomes) to avoid memory issues
    CWL -- aim for larger chunks to allow batching and multicore
    old style -- larger number of chunks for better parallelization
    """
    if analysis.lower().find("rna-seq") >= 0:
        return 50
    elif is_cwl:
        return 20
    else:
        return 200