It doesn't have to be expensive to test this claim, if you're skeptical.
After reading Steve Nugent's white paper, I used Apogee Wyde Eye and made up two cables, in 1-metre and 1.5-metre lengths, using Canare connectors and silver solder.
(Apogee Wyde Eye is one of the best-regarded inexpensive digital cables and was a Stereophile recommended component. Canare connectors are also inexpensive.)
I listened to the same music, using one of these cables each time. I did this with a pal, first in his system and next in my own. IIRC he was using a Theta transport and a Kora Hermes DAC with Siemens cca tubes. My own system was a TEAC T1 and an Apogee DA-1000E-20 at the time.
In either system, we both felt there was no doubt that the longer cable provided increased resolution. Instrument locations were more defined, soundstage height / width / depth were improved, timbres were more complex and natural.
I reported these results to UHF Magazine. They ran the test that Mr. Nugent refers to above, and as a result no longer recommend any cable length but 1.5 metres.