For what it's worth...
We install drop wires for the troffers, usually get the ceiling contractor to install "extras" for the fixtures, and any cabling that requires support.
The fixtures get a drop wire on each corner, and dependent on the local AHJ, some locations get "screwed/clipped" to the grid...some don't. The drop wire we use for cabling support gets a Caddy "yellow placement clip" to "secure" the drop wire to the grid.
When ductwork gets in the way, we improvise as needed, EMT trapeeze, etc., etc. Hell we've been known to use a tin knockers support strap a few times.