Type of drive makes no difference.  The size of the spool file is highly dependent on the type of printer and what you are printing.  For example, if you have a wide format printer and you are printing 40x60 inch prints, that's a big file.  If you are printing 8x10 prints on 8.5 x 11 paper, that will be smaller.  The current printer driver resolution matters too: 300, 360, 600, 720, etc.  You can calculate it yourself if you like.  An 8x10 print at 600 PPI would be (8*600)*(10*600)*3=86 MB.  A 20x30 inch print at 720 PPI would be (20*720)*(30*720)*3=933 MB.  And if you are printing two of them in your job, it's twice that: 1.8 GB.  And so on.  That's how much data Qimage is sending to the driver.  There is some overhead in the spooler that will make the spool file a bit bigger than that but those numbers will get you in the ballpark.
Regards,
Mike
Thx for usefull feedback, Maarten