We received some valuable feedback from one of the schools using a trial system. It was about billing and it flagged up a situation we hadn't anticipated.
We designed the system to allow for different rates for each aircraft, type and instructor. But the feedback was about instrument training. The flying school charge a premium for this compared to their standard dual rate. After about a week's work this is now a new feature in the system!
By adding a second rate and setting the descriptions appropriately, the system will prompt for which rate to use when adding flight details. Instructors giving instrument training will fill in the flight details and choose the more appropriate rate in the form. From there the invoice is generated and sent to the student.