Among other things the factory manuals show how the products are designed to be used and how much leeway there is. Using products in ways other than this can be a reason to void any warranty claims.

Does that mean it is possible to use these products in way other than those described in the factory manuals? Absolutely, but in reality, baring poor design or production, most parts work best when used in the way for which they were intended.

If the OP feels that they have to rotate the shifters any amount beyond what is recommended by the manufacturer then there is a bigger problem here, which is fit, and most likely a better solution.