What’s the best configuration on iOS devices for handling multiple email addresses from both gmail and Microsoft (name@msn.com)?

Is it advisable to have and use all these optional email apps at the same time on my iOS devices: Apple Mail, Microsoft Outlook (both web-based and 365), Google Gmail?

And within the base Outlook and/or Gmail apps, are there concerns about including both the Outlook-based and Gmail-based email addresses in the same program? Or is it better to keep them completely separate, with only your msn.com email(s) in Outlook, and only your gmail.com emails in Google-Chrome-Gmail?