When designing a new process, it’s easy to put functionality above useability where those users are internal to the organisation. For a process to work well, both external customers and internal users need to be considered.
BPMN or VSM, that is the question. If you want to make your new process flow why not use both? They focus on different aspects and can complement a design.
During a process improvement, there can be many unplanned discoveries along the way, so it's important not to waste too much time in unnecessary documentation. Keeping it simple is the best approach.
Remember all that hard work you put in to ensure your customer experience was perfect? Well that can easily be destroyed by changes made during a process improvement.
Whilst you might not need to know how the engine in your car works, you definitely should know how your business processes are interlinked before making any changes.
On any job, knowing the best tools to use are key to success. This applies equally well to process improvement, where there are many options but some more useful than others.
Choose your process wisely. A complex and difficult problem can take up valuable resources, whereas there may be more immediate benefits to be had by investigating simpler problems that have a large business impact.