Cron – What user do scripts in the cron folders run as? (i.e. cron.daily, cron.hourly, etc)

Cron can run many scripts at the same time. In fact, in Debian there are entire directories of cron scripts (ie. /etc/cron.daily /etc/cron.hourly) that execute at the same time.

If the script executes properly at a different time, why don't you try changing the time of the root cron job to determine whether the problem is with the actual timing, or a conflict between the scripts.

I also agree with turning off the redirect to /dev/null until you have everything working correctly.

The problem turns out to be that Debian does not allow '.' in the filename of a cron job stored in /etc/cron.(d|daily|weekly|monthly). Remove the '.', and the job runs fine.