Yes, especially with the lower levels (A1 and A2.1). It is important for me that the student feels comfortable in class and is aware of what is going on at any point of the class and does not feel lost or overwhelmed, therefore I prefer to use their mother tongue. I use a lot of translation with the beginners and also explain the grammar or pronunciation by making comparisons between Spanish and English/Polish (or other languages we both know).
With the higher levels (A2.2, B1, B2) I hardly ever use English/Polish in class unless it is really necessary.