Manuscript revision deadline: how strict are these [at Scientific Reports] I am a Ph.D. student and presently dealing with my first paper that I had submitted to Scientific Reports.

I received back the reviewer comments together with a note from the editor asking me (as the first author) to revise and resubmit within 4 weeks (exact wording below*). However, my coauthors and I will likely not be able to finish the revision in time (there are only a few days left), and I am wondering how strictly editors stick to these deadlines, and if they are typically likely to close the submission altogether, or rather happy to accept the revision even sometime later. The editor him/herself would obviously be the best person to ask, however, I am not getting a reply to my request for an extension, and I would need to know soon whether to drop everything and just work crazy hours to get the revision to them in time. 


  We hope to receive your revised paper within four weeks. If you cannot send it within this time, please let us know so that we can close your file. In this event, we will still be happy to reconsider your paper at a later date as long as you haven’t submitted similar or related work elsewhere in the meantime.
I had the same issue with Scientific Reports and I contacted the staff asking for an extension. Here is the answer:


  Dear authors, Thank you for your email. This will not be a problem –
  we do appreciate that some revisions do take longer than others and we
  would be more than happy to accommodate an extension for you. Please
  submit your revised manuscript when you are ready.