Viewing thousands of PDF files very rapidly
Solution 1:
Assume the files are in the folder ~/myfiles. You can run this loop in a terminal (copy-paste):
for pdffile in ~/myfiles/*.pdf ; do evince "$pdffile" ; done
To jump to the next file just press Ctrl+W in the Evince window (to close it and open the next file).
FWIW, I am not sure how useful this would be considering that you need to view "thousands" of files...