There are three times that a hard copy review is beneficial. First is right before sending it to your editor, the second after the editing is complete (right before the final upload to get it printed) and the final is reading through your proof copy.
There is something about reading words on paper that will change your perspective causing things to stand out that were seemingly hidden before. I also think it causes you to slow down and relax while enjoying the first tangible copy of your baby.
Right before sending your manuscript to an editor, print out your entire manuscript, grab a red pen, and read it through cover to cover.
Make corrections as you go, but don’t be tempted to stop for more research or complete rewrites. Mark the section that needs your attention and keep going. Reading all the way through from start to finish will help you to make sure the flow keeps flowing.
Print it out again after all the edits are done. This should go faster than the first read through, but don’t rush. Expect to still catch misspelled words and other small problems.
After uploading you file, order a proof copy. Once you are done accosting the mail carrier and have posted pictures all over social media, grab that red pen again. This time you are going to look at the formatting too.