Do you need to flatten a file for printing, or can you send it with layers? For final prints I usually dupe my master file, flatten, size, sharpen, do a last cleanup pass, and print. However, with smaller test prints I might just send the layered files to print.
If you send a layered file to print, how does the file get turned into something the printer can print? I’m guessing it makes a temporary flattened file that the print driver spools and sends to print.
I’ve never seen a difference in print quality or appearance between layered and flat files, just processing time in Print-Tool.