Interesting points. Here the prices went down on Sunday (well, that is when I went online to check). They do tend to go up a bit on Fridays, but not by that much! It varies by city, the gas stations near my sister's house in Toronto did price changes at least twice a day, cheap in the morning, expensive it the afternoon, cheap again later in the evening. Every day.
Re deliveries, why would they stay the same for a weekend where people tend to do more driving? Any long weekend sees more traffic, since people will do trips that are not worthwhile on a regular weekend. Businesses know this, they can certainly plan for it.
I noticed it simply because I am now driving less (retired, you know) and was heading into town that day for an activity. Gas is much cheaper in Ottawa (or outskirts) than in my little town, so I plan accordingly. Ottawagasprices.com lets me plan where to buy on my way in.
Re the nozzle, it varies with the station, but most have one nozzle (a second for diesel) and the buttons. Most have regular on the left, premium on the right, and the in-between one is in the middle if they have three grades.
I trust we are all frugal /sensible enough to choose cars in the first place that take regular? Or diesel? I am tempted by diesel for my next car (whenever that happens, my car only has 150,000 km right now) but a colleague of mine got stranded on the highway one winter because the preheater (or whatever it is that keeps the fuel liquid) stopped working and so did his car. At least that doesn't happen with gasoline.