As a systems admin & developer
I use different personas in Production and QA.. so that a script in QA doesn't go awry and inadvertently do bad things to production systems.
As a systems admin and a user
I use different personas for my day to day email activities, so that if my email account were to get virus-filled spam, or if I were to surf the web and hit with a zero day, the maximum harm that virus could do is affect things my user account has access to.
As an employee and personal user
If I were to do work-related business over a personal email account, then any legal issue my office runs into may allow them to sopena the emails in my personal account. Depending on what I say in that personal account that may be undesirable. This is especially important for FINRA-covered registered reps (for example) as any financial advice they offer or claim they make, it must be monitored by a 3rd party (such as Smarsh, or internal compliance review).
Disclaimer / IANAL
I focuses primarily on email in the above areas since that is where I work in day to day activities, but I'm also not a lawyer and don't know the local country/region laws that affect you. The stewardship that each user must maintain for separate accounts (or identities) may be ultimately defined as the amount of legal risk that the individual or company wants to take on.
Finally, the more accounts that your users use to do business in, and if that business has its records subpoenaed, then the legal costs have just increased unnecessarily. From a cost savings perspective alone (risk mitigation) then separate accounts may be warranted.
On the flip side, I have seen people use many accounts and not worry about this because it would cause undue burden on the business. I'm not sure if this argument holds water, but it has been done. I just hope those people never get sued.
Is it worth it to have many different personas? I'd say it depends on why you're doing it. Loss of data, service availability, and permission elevation would be one of many reasons to do it.
The general user should
- Use different personas (usernames and passwords) for banking vs forums and email
- Create a generic account that, if hacked, nothing important is lost.
- Limit exposure with the generic account by setting up multi factor authentication (lots of good links there)
- Create additional generic account as the risk exposure dictates