How to schedule Plesk updates to night hours?

Some may be worried that Plesk updates (or other periodical tasks of Plesk) occur during their business hours at their machines. The exact time of running these scripts is defined at /etc/crontab file of your OS, i.e.:

#> cat /etc/crontab
...

# run-parts
37 * * * * root run-parts /etc/cron.hourly
17 0 * * * root run-parts /etc/cron.daily
4 0 * * 0 root run-parts /etc/cron.weekly
15 5 10 * * root run-parts /etc/cron.monthly

In my case all daily routines would launch at 12:17 am (00:17), but on other systems this time may be different and you would need to adjust it according to your preferences. 

One of probable reasons is that OpenVz and Parallels Virtuozzo Containers would randomize  cron schedules for better balance between multiple containers.