As I mentioned, here are my initial thoughts on the 3 suggested methods. This overview doesn't include the serial number generation, it's just about working with the sets of 6 images and common template image:
Stack Documents to Sets of N Layers script:
PROS: Generic script for stacking and saving files to layers saving you the heavy lifting, files are alphanumeric sorted and source files are 1:1 px size
CONS: Requires the end user to create an action to do the stuff that the script isn't designed to do, so you need to be somewhat proficient at planning and creating actions as it's not always just a case of blindly pressing record and stop.
__________
JJMack's BatchMultiImageCollage.jsx or possibly BatchUpdateSmartObject.jsx scripts:
PROS: You can add alpha channel placement windows (named Image 1 to Image 6) to your existing template, files are sorted in whatever order the script was designed, from memory, this my need to be updated to enforce alphanumeric sorting
CONS: Untested, but from memory, you may need to adjust to remove masks and the images may or may not be 1:1 px size – you would need to double-check, it's always possible to change the script, just as my script it was designed to be generic and everyone has different requirements, it's the same for JJMack's scripts – making generic scripts is difficult to account for specifics to different workflows. A secondary batch conversion to TIFF is required.
__________
Photoshop Variables using Pixel Replacement:
PROS: The image list spreadsheet will be used as the order of image placement.
CONS: You need an image list in a spreadsheet, which is not hard, just a requirement. You would use the "as is" sizing to retain the source pixel sizes for each replacement image and you may need to make adjustments to the positioning (untested). Output is PSD, so a secondary batch conversion to TIFF is required.
... View more