We describe the use of a statistical technique called Tpattern analysis to derive and characterize the routineness of tasks. T-patterns provide significant advantages over traditional sequence analyses by incorporating time. A T-pattern is characterized by a significant time window (critical interval) that describes the duration of this pattern. Our analysis is based on data collected from shadowing 10 knowledge workers over a total of 29 entire work days. We report on the statistics of detected T-patterns and derived correlations with participant perceptions of workload, autonomy, and productivity. Keywords Temporal patterns, T-patterns, routine tasks, stress factors ACM Classification Keywords