Some websites I used to spider has gone mobile-friendly.

Example: <http://www.intalink.org.uk/timetables/>

which is menu-based.  A typical link (the first entry under Town Maps) is 
<http://www.intalink.org.uk/download/3767.4/berkhamstead/>.

When clicked, this uploads a file berkhamstead.pdf.

The intermediate part of the link (3767.4) is different for each file, I
think, and may not even be stable over time.

I have not managed to come up with anything which uses the urls on the page
(within menus) to download the full set of pdfs.  Is this something I should
be able to do or does the design of the website essentially rule out
spidering?