I use more than one Claude subscription. Most of the reason is usage: when one account runs low on its limits, I want to keep working on another. Claude Code normally has one login, so moving to another account means signing out and signing back in through the browser each time.
/claude-account is a command in my fork of pi-claude-bridge, the pi extension that runs Claude models through Claude Code's Agent SDK. It keeps several Claude accounts signed in at once and lets each pi session choose which one it uses. The account is a setting on the session, separate from the model, so I still pick Opus in /model and choose the account on its own.