Exactly and this is a critical fit issue. We all know you shouldn't ride in big-big but one time at least, due to brain-fade or needing a lower gear in a rush, you will wind up in that combination. The chain must allow it or the resulting damage will be quite impressive.

The Shimano method works but assumes you are within their published tooth differences and total teeth ranges for the rear derailleur, chainrings and cassette. If you take any liberties with these recommendations, the chain maybe too short.