We use waitForTicketDurationMillis to calculate the total blocked time of an operation but we also individually report waitForTicketDurationMillis. In all current uses of waitForTicketDurationMillis, we also call _sumBlockedTimeTotal. If we set waitForTicketDurationMillis in sumBlockedTimeTotal, we can avoid calling the locker twice and avoid callers of sumBlockedTimeTotal forgetting to set waitForTicketDurationMillis.