A new run - Day 7 at 12:00 a.m. This is a 21.0-hour improvement over my last run, mainly due to optimization of my military campaign - new route, leveraging fast travel to fight on multiple fronts in Arrakeen and Tsympo, grinding for Harkonnen Captains to avoid having to espionage a few fortresses, and expending an extra two troops to defeat Arrakeen-Tabr and Arrakeen-Timin faster. More details in the video description if anyone is interested.
One interesting discovery I made during this run that I haven't seen described elsewhere. There are at least a couple instances where you can fast travel between locations in one direction but not the other - (i) Bledan-Timin -> Bledan-Tabr takes no time, but Bledan-Tabr -> Bledan-Timin takes one time period, and (ii) Haga-Clam -> Haga-Harg takes no time, but Haga-Harg -> Haga-Clam takes one time period. You can shorten the Bledan-Tabr -> Bledan-Timin and Haga-Harg -> Haga-Clam trips so that they take no time as well. When using either a worm or an orni to travel from one of the starting fortresses (Bledan-Tabr or Haga-Harg) to one of the target fortresses (Bledan-Timin or Haga-Clam):
When selecting the destination on the map, click on the desert - not the actual target fortress - in the general direction of the target fortress;
Travel ~10 seconds so that you move a little closer to the target fortress;
"Change destination" to the target fortress; and
"Skip to destination."
See 1:22:40 of my video for an example. I'll post here if I find more trips where this works. Note that I use CD-ROM version 3.8 - haven't tested this on other versions.