An intern is not an employee

Worked example

What the practice could have done

A headcount of twelve employees, so fewer than twenty: three simultaneous interns at most. The fourth is in excess. The post targeted is that of an employee who left, held on a permanent basis: an internship cannot answer it. Had the practice hosted an intern for six months on that post, it would also have had to wait two months, one third of six months, before hosting another on the same post.