Hi @sam nick ,
Yes, I think it's good approach to have separate ADFs for different projects/repositories for different set of pipelines. You can also setup a CI/CD Pipeline for your ADF projects. This will help you to manage separate ADF environments (development, test, production). Please refer to this documentation for more details.
Please "Accept the answer" if this helps or let me know more details about your scenario.
More references:
best-practices-to-implement-an-azure-data-factory
azure-data-factory-3-ways-to-integrate-adf-pipeline-with-azure-devops-git