I suppose it comes down to what you expect to change individually.
If you have 300+ things in a scene where you expect each to change in isolation - e.g. for each to have their own versions - you are doing something wrong.
Determine what changes together and what changes separately. For example, a character
Instance might consist of both a body mesh, and a clothing mesh, and perhaps no need for them to be treated separately.
Do you mean in The Deal? I don't have it in front of me at the moment, but doesn't it have about 5-10 instances at most? 5-10 seems reasonable I think, but again, it comes down to workflow and what you expect to change individually.