Bus or star - it's up to you how you distribute power.
But voltage drop applies to both AC and DC and having several feeder wires is essential.

For temporary table layouts you can get away with one feeder for 20+ meters of track.
For a permanent digital layout with scenery, I would go for one feeder every meter - or maybe even more.

When using a large temporary layout in analogue mode, when running a modern digital Köf II you will not notice any voltage drop. But with a Märklin 3015 Crocodile the effect of voltage drop will show massively.
Pick a power-hungry loco for the test runs.

If you try to determine the voltage drop with a volt meter, make sure there is a huge current draw at the spot where you measure the voltage - one or two dozens of light bulbs should do.