For USCIS, it doesn’t push it back. If you submitted your case and awaiting a decision, that means they haven’t gotten to processing your case yet, and that you are still in line. if you add additional unsolicited evidence before they get to your case then once they finally do, they’ll have all what they need and won’t send you an RFE. An RFE is what makes your case take longer to a decision. For NVC, if you are DQ and need to add more evidence, don’t. You can take the new evidence or updates to your interview

1st of all it does not push back your cases because most of our cases is just sitting there without anyone even looking at it. if you have additional evidence go ahead and upload it so it’s there when they actually decide to work on your case.

depends who you ask, honestly. some say you shouldn't complicate things by uploading extra stuff, some say you should do it and it doesn't hurt to upload additional evidence. personally, we won't be adding anything extra since all we can add is more photos and phone screenshots which honestly don't make that big of a difference in the grand scheme of things. what's important is solid proof of you two living together as a married couple, same address, shared finances, marriage certificate and other stuff that any legit couple would have, but this you should have sent in at the start of the process. you can always bring extra photos and screenshots to the interview once you reach that stage.

@gen tonytony my case for my husband in the UK has said in active review since June, so just last week I uploaded more documents as unsolicited evidence. Can't hurt at this point I figured!