At this point of my PhD studies and teaching under graduate students, I use EMI when there is another teacher who is not using Finnish in teaching. I ensure that students understand what we expect them to do or learn. However, I am not teaching the same things in Finnish. I only answer if they ask something that they did not understood or I will continue the teaching in Finnish or English.
I think this style is good for the new (first or second year) students who are not so comfortable to use English. They will learn it in action. They have to use English in their studies and work life if they continue in this field.
In the future, I will use EMI in lecturing and lab works. It is good, because it is much more clear language to use in our field. We have straight orders and cause-effect relationship when the English do not give too much flexibility to understand something wrong. Nevertheless, there is a problem, when a student or a teacher do not understand some word or sentence which meaning is decisive. If the language does not bend, this might be a dead end.
From a student perspective, there is a good teachers and “bad” teachers. Both of those use EMI in different way. Sometimes when the grammar in EMI might be good, the accent is so strong that the listening is taking the energy from learning.