While using regular date/time specifiers, like shown below, any number of spaces can be used between time & user:
*/15 * * * * root cd / && run-parts --report /etc/cron.15min
However, only a single space is allowed when using special specifiers like @reboot:
# treated as valid
@reboot root /etc/cron.daily/report-zpool-status
# treated as invalid
@reboot root /etc/cron.daily/report-zpool-status
