In 10.0 and higher, logs older than 15 days are automatically cleared.
That can be enabled for R9.1 in M040 and higher as well, but the default
behavior was not changed in an MOR so as not to cause any surprises.
As for the Tomcat "cache", one should only remove the contents of
Tomcat's work directory when applying a patch, MOR, or customizaton
update -- but one should do so in these cases. [Actually in the case of
the customization update one can avoid clearing the work directory if
one ensures the modification dates of the resulting files match the time
when the customization update was deployed, rather than when it was
developed.]
