When we write a manuscript to publish a scientific project, we send it to a journal. The editorial office determine whether they will send it to a few specialist reviewers (or, reject it outright).
Once the manuscript is sent to reviewers and the editors get the review results, the editors determine whether they accept it for publication, or ask the authors to revise, either major or minor revision (or reject it).
Most of the time, "accept" at the original form do not happen. All the manuscripts I ever submitted went through one or two revisions before they were accepted for publication. That is how it works.
On March we submitted a research manuscript for a journal, and they requested us to do a major revision on May. So we have been working on doing suggested experiments, generating the data, reformatting the figures, and working on the manuscript.
A postdoctoral researcher whom I have been working with for the project dropped off the data required for revising the manuscript on Friday. I spent some time to work on the manuscript on Saturday. Now we should be able to address all the issues pointed out by the reviewers, provide point-to-point response in a rebuttal letter, and the revised manuscript should include all the response.
One thing I noticed for this revision is that they are enforcing stricter policies for scientific rigor and reproducibility, and requesting us to include information involved, such as statements for animal randomization or blinding and clarification for statistics and sample numbers.
There were some scandals in science in the past few years. As a response, they (e.g. NIH) are introducing new grant review criteria, emphasizing scientific rigor and reproducibility. The stricter requirement by the publisher seems to be a part of industry movement to emphasize quality in science.
Probably it will take 2 more days to finalize the manuscript for re-submission.
This is a part of the work as a scientist. We just do that.
In case you are interested in knowing how scientific publishing process works, this is a concise guide by the Nature publishing group, which is a major publisher group in the industry. Link: http://viewer.zmags.com/publication/64975067#/64975067/14