I do this quite a lot just for printing purpose and only for coulor scans. Usually, it adds a clean but plastic look to it.
You may play with the chart, but I found the best way to do is the way you did for each photo. Even using the same noise pattern for the same roll is not efficient. I failed using decent sharpening with this tool.
With B&W I found it very bad (meaning I really accept (noise/grain)) for those negs.
For color shots, it may be usefull for large prints (let say 20*30cm) but I use it with moderation (until color noise is acceptable for my point of view)