Nobody practises the interview out loud. VisaRoom is where you can.
Most people prepare for their German visa interview the same way. They read old forum posts, collect questions in a WhatsApp group, and go over the answers in their heads.
Then they sit at the window and say those answers out loud for the first time, to an officer, with a lot riding on it.
VisaRoom is the rehearsal. You hear the questions, you answer them out loud, and afterwards you see what each answer missed, including the places where your answers didn’t match your own documents.