With the practitioner performance report, there's a column under the revenue tab that's called service hours:

These are defined as the total number of hours that a practitioner has seen patients. While someone might be at the clinic from 9 to 5, they aren’t necessarily seeing patients for eight hours straight. Service hours are calculated by looking at the duration of all appointments (both individual and group) that have been attended by patients during the report’s timeframe.

For example, let’s say you run a report for the first week of March. Sally the Physiotherapist was in the clinic from Monday through Friday, 9 to 5, but she wasn’t seeing patients for all of those hours. On Monday, Wednesday, and Friday, she had four hour-long appointments spread throughout the day, and four half-hour appointments mixed in. On Tuesday and Thursday, she had three two-hour appointments, and nothing else.

One patient cancelled their hour-long appointment on Wednesday, and another didn’t show up for their half-hour appointment on Thursday. Sally marked these appointments as “cancelled” and “Did not arrive”.

Using the example above, Sally was in the clinic for a total of 40 hours, but she was scheduled to see patients for a total of six hours on Monday, Wednesday, and Friday, and six hours on Tuesday and Thursday. Her total “service hours”, in this case, would have equalled 30 if no one had cancelled or not shown up—but because there was a cancellation for an hour-long appointment and a DNA for a half-hour appointment, Sally only actually saw patients for a total of 28.5 hours.

Note that service hours don’t include admin work or “non-appointment” time, so Sally was probably busy writing notes after appointments, following up on emails, and doing referrals—but she only saw patients for 28.5 hours in total.