Image file resizing for print output

To add to the others - as long as you DON'T switch off resampling settings in the PDF Export profile - InDesign will automatically resample all your graphics so there is really no need for the extra work.

And even if you would include all the data from your images - you won't get better results - finer details - as the printer have limited resolution anyway - and people who will have to process your files ... well ... I wouldn't want to meet them face to face if I were you 😉

I used to work that way as well (and a Photoshop action might be the way to go to speed things up). I wouldn't do more than Eugene suggests now except for a museum catalog or fine art coffee table book printed at a very high screen value.

You might have to reprocess a severe size reduction, but in general full-size images that have been properly processed export just fine.

Is there really a need to do this - or are you're adding a massive amount of work that is not necessary?

Place your files from the 100% size source.

And export your PDF choose your compression settings. 

That should be about it. Is there a reason for this, are they colour managed images or images that require sharpening every time you print them for different reasons? 

300 PPI is a faux number too - it only really applies to lithographic printing - where 300DPI is derived from the LPI output of the device - which for a lot of Lithographic printers would be about 150. For newspapers, this number is lower and for high-end coffee table books, etc. the number is as high as 175 or even 200. 

The LPI is important as a lot of people multiply by 2 to get the required DPI of their images - which for 150 typical print would be 300 - but the x2 number is erroneous. It should be 1.41 - which for a 150LPI would require a DPI of 210 - not 300. 

1.41 is because a halftone square is rotated 45 degrees and measured from tip to tip - which is always 1.41. 

So if a square is 1 x 1 - the diagonal between the corners is always 1.41

 For me - place the images at the original size- no changes - and control the compression and colour conversions directly from InDesign.

If you really need to sharpen all your images all the time - can you not sharpen just the original image and save that as an optimised sharpened image?

Forgive me if your workflow requires retouching images for a specific control reason.