It's tens of feet -maybe even a hundred feet of wire in a giant LF inductor set up for a very low crossover point.
No maybe. If someone makes a design choice to use an air core inductor on a woofer circuit in a 3 way, it does not even need to be that low of frequency for there to be a couple hundred feet. Go for a low frequency and you can be above 500 feet of wire. Then they may compound that by using Litz increasing the resistance without benefit.