It seems to me bracketing exposures is only useful if you process your own sheet film
I have shot 35mm color roll film bracketed and taken it to local lab for 'normal' processing and the stock prints returned all look the same. There is no evidence of my bracketing in 36 images. This means to me that perhaps the 'lab' compensates for over/under exposure in their processing of normal.?
So I feel bracketing is only effective in the development stage of sheet film where processing compensation can be applied one neg at a time.