Once a mishmash io cluster is deployed on Microsoft Azure it can host the data of multiple apps.
If you're developing multiple apps that need their own 'isolated' database - you can safely co-host their data on the same cluster. If you don't specifically allow access - they won't be able to read or write each other's data.
A typical example might be if you're also developing apps for internal use by your colleagues only. These often have lower requirements, as they're not as busy as customer-facing apps. Such apps don't need an entire cluster and their data can be co-hosted with other apps.
Default alert:Arrange in tiers
Cluster resources can also be arranged in tiers: heavily used apps can get more computing power than others.
Two apps - My app and Company CRM share the same mishmash io cluster - mishmash io.
The two apps in the example above can also be deployed with separate mishmash io clusters.