[quote=“georage”]I’ve never done it, but it sounds very German and unnecessary.
Simpler methods produce fantastic results.[/quote]
Depending on your water profile, it might actually be less complicated to add the dark grains during the sparge rather than having to add chalk to the mash to balance the pH.
The point of cold steeping or adding dark grains during vorlauf is to reduce harshness and bitterness. One added benefit, is that you don’t have the higher acidity of the darker grains bringing down your mash pH (which, depending on your water, may require the addition of chalk to balance). Another, is that you can add the cold steeped extract in increments to taste.
It definitely isn’t necessary to use these methods to brew an excellent beer using darker, roasted grains, but they can be useful.
By the way, if you’re going to cold steep you need to let the grains steep for longer than 30 minutes (more like most of the day).