Depends on the reels and tanks.
For instance, did you use less chemistry in the steel reel tank? If so, it will exhaust more quickly.
Also, some reels are designed for use with longer films. They do that by providing a narrower space between each layer of film and steel in the reel. So if you don't get the film correctly into the reel, it is more likely that two layers will contact each other. In addition, with each layer of film being closer to the next, there is of course less room for chemistry between them. So if any chemistry is being trapped, it will exhaust more quickly.
By the way, you may want to consider continuous agitation for the first 30 seconds of fixing. Kodak at least recommends that, plus further agitation at 30 second intervals.