Every connection you make in the cable will loose about 0.5 dB. Four cables made into one then will net a loss of about 1.5 dB compared to a solid single cable. 3 dB is a 50% loss, but dB is a logarithmic scale not a geometric scale, so I estimate that to be maybe about a 25% loss in three connections.
A shorter cable would have slightly less loss also.
As for quad shield, it is to prevent local strong interference from penetrating into the wire. If you don't have other signal sources or sources of RF nearby, there is not really any need to go quad shield.