In most of the implementation I have seen the different metastore for prod and dev i.e one metastore for dev and test and another separate metastore for prod but in that case databricks account is also different for those environments.
For the cloud the tenant will be same but the subscription will be different.
The real logic is how you assign your databricks workspace to the metastore. At a time one workspace can be part of only one metastore but one metstaore can be part of multiple workspace.
And it's also depends on how the data isolation you want and at which level? If there is requirement to have the multiple metastore as per the different domain data or due to some other compliance rule then you can have it.