When it comes to the new speaking tests we have decided to keep things simple for us and for the students. To do little 5 minute tests at various times over the course seems messy and confusing to me. For students also there would be no sense of occasion and I fear they would under-prepare for tests. I hear the argument that students under-perform when under the stress of the oral exam, but this has not been my experience over the years. In fact, I would say the opposite. When students prepare carefully for an "event" like an oral, they usually prepare thoroughly and perform above their normal classroom level.
So, we have decided to essentially do what we do now. We'll collapse the 5 minute "dialogues" into 10 minute orals. We'll teach a sequence of lessons on our chosen topics and then do an oral at the time of mock exams (November). We'll note the marks for this and then give students a second go later in the year (May) so that they have had a chance to a re-sit.
I imagine that in the rare cases of students who have a really bad day, we could arrange for an occasional third attempt.
I am pleased to see the demise of the role play and the learned presentation. Although the latter was supportive of weaker students, the new format for conversation will still allow for considerable pre-learning.