Hi Richard - You are unable to schedule hundreds of training sessions using an excel file.
But what you could do is schedule up to 30 classes using the "Schedule irregular sessions" in the Occurrence area. At the bottom create a scheduling template so it remembers all your settings then using the template pull down menu - top left, schedule another 30. The caveat here is that it would be the same class. For different titles you'd have to change the class title.
