Dynamic Timesheet Compliance Flag (90% Threshold)

I want a dynamic flag created based on time entries and a person's working hours. This flag would assess whether a person has 'accounted for 90% or more time' in a specific period (e.g., last 7 days, last 30 days). With this flag, I could filter all reports to identify people who haven't submitted timesheets and need chasing, or identify people who are 'safe' to include in utilization reporting.