The expensive oil change is one of those "extra dealer profit" items that Harley dealers have been abusing for a long, long time. The simple answer to the question is, most dealerships don't actually do the entire checklist, and many don't do anything other than change the fluids. And these "service interval" jobs are normally assigned to the least experienced techs in the dealership, so don't expect any kind of a detailed analysis of your bike. They might wipe the metal debris off the drain plug magnets, but it is unlikely they will analyze the quantity and composition of the debris in an attempt to find a potential problem.
If you are handy and enjoy working on your own bike, you would be better served spending some of that money on a shop manual for your model and then doing the service yourself. That is probably the only way you would be 100% certain the entire checklist was done. And if you aren't the mechanic type, find an independent shop and develop a relationship with them. You don't have to go to a Harley dealer for maintenance.
Figure approximately $10-12 per quart for fluids, about $13 for an oil filter, and less than a buck for a couple of replacement O-rings for the drain plugs. If you are careful removing and installing the derby cover, you won't need a new gasket each time. Add in $60 on the first service for a shop manual, and you are still looking at less than half of the dealer's price.
Jerry