I really need to get an idea in my head of how wide the chasms between plateaus are, because I'm thinking sometimes we imagine them to be very wide, and they don't need to be.
Think about it, though... a gap of 10 feet is too far for most people, especially weighed down with armor and weapons, to jump with any reasonable expectation of success. For scale, I think the average US residential street (two lanes, no dividing line, no shoulder) is about 20-25 feet wide, which seems a lot wider than any of the spaces that Bridge Four was exploring down below, so it sounds reasonable to say that's probably about the widest gap a bridge crew covers, (unless the text of the book directly contradicts me). That's sufficient distance for a 50-foot bridge, weighted to the rear, to cover if the opposing edge is just slightly lower, and lets remember that ANY gap wider than maybe 6 feet probably requires the bridge crews to drop their bridge.
Does someone with a ebook version want to keysearch and actually transcribe or C&P what is actually written about the dimensions and shape of the bridges, as well as the dimensions of the gaps? I remember vague details such as the wedge-shaped ends and the hollow interior and that it's something like 5 men across and 10 rows deep, but that's not solid measurement.
On the issue of soulcasting bridges:
Soulcasting is more than holy, it's expensive. Wood and lives are cheaper.