The site I am mirroring grows by one (and only one) new top 
level webpage per day and is an archive going back seven 
years.  Having captured the older pages, I now only wish to 
concentrate on the newest entries, that which have appeared 
only in the last few days.  

Any of the webpages dated more than a week old are no 
longer of concern.  They do not change, except for links 
that may have expired.  I have set the "Build > Do not 
purge old files" option, so any expiring links are 
irrelevant.

How can I limit the site update to the most recent top 
level additions?