Well, tbm, it all depends. It depends on the maximum magnification of your enlargements, the overall cleanliness of your process and what you are willing to accept. There will probably be times when you want to filter solutions - especially with 35mm.

I really hate to "spot" prints and/or negatives. When I digitally scan negs, I do so with Digital ICE disabled (I hate what it does to the microstructure of the image). If I see any negative debris or damage, I look at my process to see what went out of control.