Several depends-on things come into play. Usually, the length will not matter, so long as the coaxes are the same impedance, have proper connectors on them, and are not so long that they get looped up. (The looping can act as an inductance coil under the right circumstances adding 'loading' to the circuit. Also, when used for a specific frequency, such as a repeater, or as a digipeater on HF, length can affect, and of course the fact of whether it is fully shielded, or like radio-shack coaxes only partly shuielded. Velocity plays as big a part in detuning an antenna circuit, as it can create heat/resistance and therefore SWR increasing.  Also, there is a loss per foot that will limit how long things can be in setting them apart. Different 52 ohm coaxes will have different loss per foot ratios as well as being more suited to one frequency range (Band) or another. Good Luck, es 73 de John Jewkes, W6HNC