Braiding and/or weaving *is* necessary if you want the multiple strands
to work like Litz wire and reduce the AC skin effect inherent in all single
element *or* non-woven multiple conductors.
If the wires are bare, they form a single conductor. If they are
not, they form a litz wire. No weaving is required. Woven litz
functions better, but is NOT a requisite to see the effect.
The skin effect is not being reduced with litz wire, it is being
exploited. Maximized even.
The multiple strands each have their skin, and that total skin area
is increased, giving the wire a larger apparent size, from the
perspective of the high frequency currents on it. If the wires are
bare, they meld together form the current's POV.
So, if it is more than one element, there will be a reduction in
impedance on the wire at higher frequencies. Period.
It does not require that it be RF either. It does not require
weaving. All that is being done is that a "skin" is provided to the
current flow in areas of a given wire bundle that would normally NOT
be provided in a single strand, or bare bundle.
So, as l;ong as the wires are isolated from each other, there WILL
be a skin effect for all non DC use above a dead slow frequency.
In other words, there is a propagation delay, but it doesn't require
RF to show an effect, and therefore a benefit.
Even the power line boys know that, and they are at 60Hz, with their
bundles separated by 4 inches of air between each strand.