Not all Site Valet jobs run under the supervision of valetd. Some are too simple or too infrequent to merit it. These should instead be scheduled to run as cron jobs. They can run daily or less frequently; in most cases a daily run will work well.
These programs are located in $VALET_BASE/sbin and require the Valet environment.
MailReport is the program that generates and sends email reports as specified in the domains configuration. A good schedule for MailReport is to run it daily just after midnight. Running it more than once a day is inappropriate (but harmless), while running it less frequently may have unintended consequences where domains are configured to be reported only on selected days of the week.
PurgeDB purges obsolete data from the Site Valet database. This is primarily required when a change to the domains monitored means that some of the data are no longer relevant. It also serves to cleanup when a site is reorganised and some URLs disappear.
PurgeDB can run infrequently; a weekly or even monthly cron job will work perfectly well for most users.
PurgeCache is a trivial script to remove old files from the Valet workspace. This serves only to save disc space. It can run daily if disc space is tight, or less frequently if it is not an issue.