Normally if the captain was PF on the first sector then the FO would do the approach for the captain's landing. On the next sector (all things being equal, weather etc) the FO would be the PF and the captain would do the approach for the FO's landing. The nice thing about this procedure is you get to have a 'play' on every sector and the FO's still get to practice all the things they'd practice in a non-'monitored' approach i.e. they still get to learn from their mistakes.
Fair enough. On the west coast of the Atlantic, the prevailing theory is "your leg, your controls"- up to and including the next approach after you've messed up the first one. Obviously, the PM is will speak up if he's not comfortable, but it's not atypical for a CA to sit back and watch the FO mess up (within reason), and use it as a teaching moment.