I would think Friday and Monday are the worst days.

No. Based on my experience as a hiring manager for a long time the day and time of the interview matter, but not when you apply. In our case there is a specified, published open period to apply, and I will review them as they come in, logging in and checking 1-2 times a day. Whether someone applies the first day or three weeks later makes no difference to my decisions on who gets an interview.

No real rule. I think people will tend to think Mondays/Fridays are bad because we tend to not be focused on work. However, when you send it and when the hiring manager gets your resume may not be directly correlated. As a hiring manager - I would receive resumes from HR. HR may be checking it every few days. So if you sent it on Monday, they may not check until Wed. Send it to me, on Thursday. But if I'm busy, I may not go through it until the following Monday. In that sense, it matters little when you actually send it.

I don’t believe there’s any day that’s really advantageous.

The best day of the week to send a job application is when the job posting is first posted. Early to apply tends to have better luck.

Wouldn't necessarily think so. Monday can be a gloomy day for many, but it's also the start of another week, and some organizations may be primed for getting action and new candidates from the start of the week. So two very different forces in effect. Friday tends to be a positive and happy day for many, but things may be winding down then, and slowing down for activities and following through with actions and hiring. Maybe Wednesday is the right balance? No way to really know unless your on the inside. Also, you could send it in one particular day (say Monday), wanting it to be read then, but it might not be until Thursday that they get to it. So it's really a crap shoot.

It doesn't matter. As well as the best resume. There are some doozy. Good gawd.

As long as your resume is good enough, it doesn't matter when you send your application.

Sunday nights worked well for me.

Weekdays I guess? Especially during afternoon.

I'd say no. Resumes get looked at even if briefly. It's not an interview just a prescreen. If a job requires a resume before an application/interview that probably means their looking for something specific. If you have it be it a Monday or Friday you would still probably get additional consideration or an interview/application.

Ideally, I'd submit it on a weekend so it's at the front of the line come Monday morning, but like everyone else said, who knows when it will actually be viewed.