I’m not a big fan of Marks, but he is essentially correct, and I’ve done videos on this myself.
Firstly, when you view a print hanging on a wall, to take it all in, you will be viewing it at between 2.5x and 1.5x the diagonal of the printed image. Only idiots put their noses up to a print!
Modern printers usually print at a maximum of 5760 dots per inch, and 1440 dpi is considered a fairly low resolution print.
Just because the image might be stored ‘in archive’ at 300PPI (not DPI) the majority of fools on the internet seems to think that printers PRINT at 300 dpi - like I said - FOOLS. I have yet to come across a printer driver that will accept such a low setting as 1 pixel = 1 dot.
But; even in archive form at 300 PPI, you are viewing the image on your monitor at a MUCH LOWER resolution. I use a dedicated photography monitor, a 27" Eizo ColorEdge, and this device has a resolution of 109 PPI.
So in essence, I’m viewing the image at 1/3rd of it’s native resolution!
If I open the 300PPI image in Photoshop and turn on my rulers set to inches, I can instantly see that those “photoshop inches” are indeed nearly 3 inches long if I hold a ruler up to the screen.
Photoshop has a function called "view at print size’, and in the preferences you have the ability to enter your monitor resolution. Do this and when I personally click ‘view at print size’ my view magnification drops, not to 50% but 36.33%.
This magnification shows me what the image would look like printed at its native size AND viewed from my standard screen working distance, which for most folk is around 20 inches.
Irrespective of Lanczos or Photoshop upsampling, print sharpening done CORRECTLY is done at the print head, and at the print resolution - so you can not preview it on your monitor. You can certainly emulate it using something along the lines of the Pixel Genius plugin, but even then, it’s imperative that you view it AT PRINT SIZE.
MM will NEVER give away the ALL of the detail in his workflow, because he wants you to pay him big dollar and attend one of his week-long courses at Nevada Fine Art Printers! Printing is looked upon today as some kind of magic juju skill that requires ‘the force be with you’, and he likes to temp you into thinking you to can have the force - if you pay him.
But to someone like me who cut their teeth on all this crap years ago in the long dead pre-press industry, it’s neither magic, juju or a force of any kind; it’s just simple common sense that I’m happy to pass on to anyone - who cares to listen!