I don't have the time to evaluate the effects of context length on my use cases so I have no idea. There might be some degradation when I attach the Qt book which is probably already in Claude's training data but when using it against my private code base, it's not like I have any other choice.

The UX of drag and dropping a few monolithic markdown files to include entire chunks of a large project outweighs the downsides of including irrelevant context in my experience.