There is no minimum cable length for twisted pair ethernet.
Minimum length of cat6 cable.
Category 6 cable cat 6 is a standardized twisted pair cable for ethernet and other network physical layers that is backward compatible with the category 5 5e and category 3 cable standards.
For completeness sake 1000base cx states 0 1 m minimum length.
Cat7 gets advertised for its 100 gbps speed but that will only work for distances up to 15 meters slightly over 49 feet.
Cat 6 has to meet more stringent specifications for crosstalk and system noise than cat 5 and cat 5e.
I have ordered 1 foot cat5 and cat6 cables for my patch pannes to make things easier.
The cable standard specifies performance of up to 250 mhz compared to 100 mhz for cat 5 and cat 5e.
It should be noted that cat7 cable has harsher distance limits than cat5e cat6 and cat6a.
In the past cat 6a cables were always typically larger in diameter because they operate at frequencies of up to 500 mhz which is twice as high as cat 6 and require thicker more materials such as outer jackets or larger splines to adequately control noise and crosstalk at these levels.
But i do know you can order 12 inch 1 foot cables from a cable vendor provider.
Copper also includes ancient coax cabling which does have minimum spacing of 2 5 m 10base5 or 0 5 m 10base2 but i don t think this was the question.
I do hope this helps.
With utp you need to make sure the number of twists in the cable meet the specs.
Cat 6 supports 10 gigabit ethernet only up to 164 feet of cable length.