Sharepoint system will not provide any alert or notification to user if any thing crashes in varaition system.
e.g. If any issue occurs it will not copy pages but you will be noticed that later when you will find broken links on your site.
It is recomended that administrator checks logs after publishing new contents to see if everything working as per expectation. Varaition logs can be location in site settings at your top level site.
If you think you are getting unexpected behaviour and your logs are not showing any useful information you may further investigate logs in "hive 12" i.e. "[Program Files]\Common Files\Microsoft Shared\web server extensions\12". You may check status of your scheduled job for locating any issues in variation. If you found that issue is due to execution of your job restart Windows sharepoint timer service using services console "services.msc" to fix issue.