I have one of my novels in serious editing mode currently (INCENTIVIZE). This is the most complex storyline of any of the novels I've written, with multiple threads, and action taking place in fits and spurts.
Now, I may be odd in this respect, but when I read a story with multiple threads, I'm okay with the storylines being a bit out of synch. I realize the author sometimes intentionally "de-synchronizes" the tale for dramatic effect. Usually, everything comes back together at some future point, and I kind of enjoy puzzling over where things are on the timelines of the various storylines.
Unfortunately, with INCENTIVIZE, I let it get a bit out of hand.
So over the past day, I put together a detailed excel spreadsheet showing the main storylines, and the sequence of scenes versus the actual calendar date.
Wow. There was some stuff that was waaaaayyyyyy off. Repairable, of course, but undoubtedly confusing to a reader.
The tool really worked well at pointing out where the sequencing of scenes needed work. I'll be using a similar tool for all future novels where there are multiple timelines involved. The next one where I know this comes up is HEIR APPARENT.