I think we have to look at this specific cast of Day as catering towards the newer players who are around plat/gold level and below. A lot of the stuff he mentions makes sense for the lower level players and/or new players who have not yet mastered their mouse control. With that said...
I'm generally a big fan of his, so I'm definitely not biased. I watched the #252 video on recommendation. Off of the top of my head:
"don't box single units" -- even pros and master league players do this. I believe it's optimal for fast play, since 100% accuracy with the mouse shouldn't be taken for granted. Even day9 does it in this very same cast.
I admit that I do box single units, I do it in conjunction with edge scrolling as to move my probe to build a pylon near the ramp right at the start of the game. Granted it's a small box, just large enough to select the probe and not four-gateway-full of space.
Pretty sure the reason he's mentioning it is for the newer players who have not yet gotten their control down and are making huge ass boxes, which is unnecessary.
It's also used to warm up your unit selection for the inevitable micro needed in battle later in the match.
Location hotkey for the first base -- you already have a control group for your base, so why make things more complex?
For me, it works immensely as I'm a Toss player. I'll location hotkey my warpgates for easy access to chronoboost in the event of a 4wg.
But for the most part, my initial Nexus will be on 4 and thus proving your statement correct. I'll also hotkey a Robo facility on 3 to jump back to my main base and for production, now that 44 automatically jumps me to the expansion.
"always box from top left" -- his reasoning is accuracy. Accuracy should be traded for speed in most situations.
I think this one I agree with you. In fact I've retrained myself to box top right down to bottom left as Tastosis recommended because you end up closer to the minimap.
But he does make a point that it's easier to box from top to bottom than it is from bottom to top. Same reason why it's easier to attack from top to bottom than from bottom to top. Mouse control.
"edge scrolling is slow/bad" -- he's demonstrating on default scroll speed. I believe with fast edge scroll speed, it can be used optimally in many situations rather than mini map clicking.
To make a point to the newer players to use their minimap. I myself use edge scrolling at 100 percent and it works for me. But I only use it for close locations, like my main base in the first couple minutes of the game, or to micro an army around a certain area.
His section on staring at the mini map is also sorta dangerous because he doesn't show how to balance it with checking mineral/supply cap. Doing this without good habits for checking min/supply could be disastrous.
I think he meant to constantly look at the minimap to check, and not literally to stare. In 132 he always references checking your supply and minerals at the top right, so if used in conjunction with this lesson then a player should always be checking every integral part of the screen. It's just part of the mental checklist we're trying to ingrain into players and ourselves.
His "tapping" section could prove useful for players that don't already tap. But yea, overall, I felt like there was a lot of misinformation in the cast that also serves to make gamers feel overwhelmed with complexity when these habits shouldn't be followed at all. These tips were meant for the mainstream to improve, but when even rank 1 masters/pros don't do these things, one has to wonder.
I interpreted this as just basic knowledge for the newer and/or less experienced players to improve, but also to keep in mind that nothing is ever finite. Everyone has their own way of playing and whatever is comfortable should be the way that they play the game.
However Day makes great points throughout that cast and while he may have overexaggerated several points such as the minimap and the mouse control, I think it's just to show that you should train yourself to use everything at your disposal instead of just what's directly in front of you.
The whole mouse control thing is useful when trying to pick out a certain unit (like a stalker) in your army cluster that you're trying to blink back. When you get used to picking out a single unit (like a probe) in a huge mob at the start of the game, it'll be easier to pick single units throughout the game for micro and what not.
Not trying to be condescending or anything, but I wanted to play Devil's advocate for this part in order to stimulate some discussion and reasoning on why or why not certain things are great.
In the end, we'll all benefit from this sort of discussion and see how we all can learn or improve!