Personally rarely above 100ft unless there's an issue with separation from the usual, a safe go-around, or the student has made such a hash of it that it's already obvious to them (as well as me) it's never going to work out. I like the student (or me when practicing solo) to have a clear picture of where the roundout and landing will go. 50-100ft normally, so long as there is nobody to annoy and I'm not breaching "rule 5"*.
G
*Yes, I know that SESAR superceded rule 5, but it's still a useful label for the principle.