Here's a good example: https://www.modulargrid.net/e/mutable-instruments-veils-2020
If you look at the bottom row of jacks (in the gray box), you'll also see a set of little arrows pointing from one jack to the next. By plugging into the #4 output, you'll get the signals from all four VCAs at that patchpoint. But if you wanted to "split" that module, you can. Let's say you have two different voices that you want to send to a Veils for amplitude control, but you also want to keep the different outputs separate. With "breakable" normalizations like this, you can pull one voice through the first two VCAs by jacking into output #2, as that will break the normalization between #2 and #3 and effectively split the Veil in half so that your other signal's output is on #4, even though you're using just ONE module.
And yes, this appears on other points besides outputs. Have a look at Intellijel's Mixup. On that, you can use inputs 3 and 4 as either stereo (by patching L-R signals into those inputs) OR mono...because there's those same arrows again, and those mean that you CAN use mono signals on 3 and 4 simply by connecting those to the "left" inputs alone. The input normalization does the rest.
DAMN useful! More manufacturers really should jump on this...