Emailing interviewer for update

I had my two first round phone interviews for BAML HK S&T SA a week ago. They said I should expect to hear back in around a week, so obviously the anxiousness around now is pretty high. I'm not planning on anything yet but, say, if I don't hear back in another 3-4 days, do you think it would be wise to email the interviewers directly asking for an update on my candidature or the next steps in the process?

One of my friends interviewed for the exact same thing the day before I did. He ended up calling the HR representative that scheduled our interviews and she told him that she has no idea about decisions etc. - her job was just to schedule the call.