|The cable specification actually includes how the entire installation needs to be performed to maintain a designed speed rating. Any variation from that spec can reduce total design length. If one disregards any of the specs you get what people notice. Things as simple as a tight bend can cause the quality to be reduced. Any EFM like lights and motors are need to be shielded or maintain distances.|
It can be that you could run a much longer length of cable and it would work fine for your application. The length isn't a magical number it is only the rated limit. For a simple enough test put two ends on a box of wire and hook it up. It will work but may default to 10M or so.
Some network devices could be much better than others. A cheap soho device may not even be up to the actual rated or could be better. As a general rule I think the more expensive stuff tends to perform as sold.
Playing to the angels
Les Paul (1915-2009)