Three reasons companies bring in an interim leader. Someone left and you cannot wait four months for a permanent replacement. The permanent search is running and the role cannot sit empty while it does. Or the next six months have a specific shape, a turnaround, an integration, a new-product launch, that calls for someone who has done it before and is willing to leave when the work is done.
Every interim placement is line authority, not advisory. The interim leader sits inside the org chart with the team that reports to them, makes calls that matter, and is held accountable for outcomes the same way a permanent leader would be. Engagements typically run three to six months full-time, sometimes longer, sometimes fractional. The same person you talk to on the first call is the one running both the placement and any concurrent permanent search.