I doubt the restriction mentioned by others would really amount to much
if you are just swooping around light fixtures. The drag induced by 4
elbows would probably be worse than that of the foil tube in a loop
around the light fitting.
By a "loop" I mean, cut an 18" long piece out of the solid duct.
Attach one end of the flexible to it.
Run the flexible past the fixture, then do a full loop around the
fixture and attach to the other end of the solid duct. Nice big radius
and quite low restriction overall.