It's not the heat escape that really matters, but the vapour
Keep holes to an absolute minimum to prevent moisture entering your attic space. A patch panel in the drywall would mean a large, significant air leaky hole and therefore the cables only would be much better for your home's vapour control.
What's vapour control and why does it matter?
Humans produce absolutely loads of water vapour in a home - through the obvious methods like using a shower, cooking or sweating, but also simply breathing and talking puts water vapour into the air. When this vapour gets in contact with a cold surface, it condenses and eventually causes rotting and mold.
Traditional home construction involves using outside air to blow that condensation and moisture out of parts of the house that are vulnerable to significant amounts of it, like your attic space. Using air in this way though is not at all efficient - it means a notable chunk of your house is drafty by design, routinely blowing warmth out, and moisture is still fundamentally contacting the structure of your house.
So, more recent construction techniques involve a continuous vapour barrier just above the ceiling and behind the drywall of your exterior walls. Its goal is to completely prevent moisture contacting the timbers of your home, meaning that the old school air technique isn't necessary anymore. But there's a catch - "continuous" really, really matters. Small holes through your vapour control layers allow lots of moisture carrying air through.
TLDR: Keep moisture out of your attic space by minimising holes to give your timbers a healthy lifespan. Any holes that do penetrate into the attic space are best being taped up with some form of vapour proof tape.