@ross.t: there's a citizen science (crowd sourcing) project which
is very much related to your questions, in a general sense, Radio
Galaxy Zoo.
Main page: https://radio.galaxyzoo.org/#/
Discussion forum: https://radiotalk.galaxyzoo.org/

To repeat what's already been said, to be visible as radio
lobes/hotspots/jets/etc, the back-to-back relativistic jets created
near the SMBH in the nucleus have to get through, and be seen
through, first the ISM of the galaxy, then the IGM between galaxies.
It's nice if both are homogeneous, but often they aren't. And there's
relative motion too, producing such things as 'narrow angle tails'
and 'wide angle tails'.

On timescales: there's a class of radio sources called "giants",
lobe-to-lobe distances as great as 5 Mpc. There are also some which
are "restarted", in at least one case, at least three times.=20

On single vs double jets, there's a rare class of object called
"hybrid" or "HyMoRS" (Hybrid Morphology Radio Sources), where the
radio morphology of one side (jet/lobe) is extremely different from
that of the other.