Whether you have a single project or multiple ( hierarchy ) as part of an organisation, you always need to know the exact amount being spent on your GCP cloud. It is further important that you narrow it down by service ( SKU ) to ensure that you are spending it wisely.
In most commercial environments, multiple projects will exist. Each project is associated with one billing account. However each billing account can have multiple projects. Projects are normally grouped using a hierarchy …. The hierarchy is as follows
1 : Report overview
2 : Report By Filter
See your cloud cost report on a weekly basis to ensure nothing is being spent needlessly without you being aware. Happy reporting.