Does creating a loom in cables in a system make a significant difference?

I think it is likely ideal… but dependent on your components. I have been working on my system for fifty years. It has been a mishmash of components for most of that time. 
 

I have invested a huge amount of time and discretionary income in my system… doubling the investment every decade. You can see where I ended up… under my user ID. All Audio Research electronics, all Transparent interconnects, cables and power cords (save one). I never set out to harmonize my electronics and cables… it happened through extensive experience, auditioning, and evaluation.
 

One day I ended up with the best system (for my tastes) I have ever heard… and it turned out to be a known synergistic set of components…. Audio Research,  Transparent, and Sonus Faber speakers. Hmm, this can’t be an accident. 

I have Kimber for speakers and interconnects and Shunyata for power/distribution.

I also added 1 item at a time and appreciated the difference.  Part of the reason was after I bought my speaker cables from Kimber - I looked at eBay for kimberdirect and bought demo's for my interconnects.  (I do have the same interconnects for source to pre and pre to amp connections.)

@styleman

I use a mix of different cables for interconnect, speaker and digital cables. I have no complaints. The music sounds great

I would say your own results speak for themselves. Different roads do lead to Rome. Same brand cable loom has worked out for many. Use your ears (As you’ve apparently done).
I have used the same manufacturer for my Line stage:amplifiers/speakers (Coincident) to excellent effect. But have two different brands of cables (Ocellia IC/SC and Lavricables power cables). It has worked out very fine for me.

Charles