Do I have to restart cron after changing the crontable file?
No. Cron will examine the modification time on all crontabs and reload those which have changed. Thus cron need not be restarted whenever a crontab file is modified.
When a monitored system uses tools to record access, the hourly monitoring request will influence these data.
This can be avoided with filtering the recorded access via User-Agent request header. The Monitoring system sends the string ContaoMonitoringClient with each request.
For example using the Contao extension [visitors], the User-Agent filter can be defined in the module:
Screenshot Module configuration of visitors
Using other tools or systems, this filter may be different.