Yes, it's paranoid, but I respect your decision to do it. However the imperative mood used in your first sentence is totally inappropriate. That's exactly what Profiles are for; the vast majority of people are going to want to process personal issues and work issues without signing in as a different user.
Don't do that. On one hand you mix work and personal related issues (not recommended) on the other hand it makes it easier to track you (as your accounts can be correlated). As a dev I have my own (personal, work, ...) users/accounts even at home (if I do remote) to separate the stuff - maybe that's paranoid, but for me it was great to improve work-life balance.