There’s very little I dislike about this product, but the one thing I fight with regularly is its approach to calculating date precision.
A simple example:
Joe is born in 1901. He dies in 1911. How old was he when he died? If you said 10 you’re probably in the majority. But Aeon Timeline says he lived to be 11. That’s because it’s assuming a 1/1/1901-12/31/1911 range.
Okay, so I understand its logic, but that leaves me having to apply a workaround to get the results I want, and there are only three I can think of:
 I enter incorrect start/end dates by shifting one or the other by a value of 1x (move the start forward 1x year or move the end backward 1x year). This fixes the total but now I have to remember that my start or end dates are always going to be off by 1x.
 I enter correct start/end dates. This fixes the dates, but now I have to remember that the total duration will always be padded by 1x.
 Whatever I’m tracking, I go one level deeper into the granularity. This means if I want accurate years I have to add months, if I want accurate months I have to add weeks, if I want accurate weeks I have to add days, and if I want accurate days I have to add hours. This is a lot of extra work which not only forces me to enter arbitrary data (maybe I don’t know/care what month someone was born, but now I have to just pick one to keep the years accurate), but it is a fundamentally bad approach because all it does is pass the buck to the next level.
I realize this approach might be great for some people. It just doesn’t work for me. For timelines at the year level I’m always off by a year, and for timelines at the day level I’m always off by a day.
Said all that to say this. I recommend either changing the way the total is calculated to be more in line with what most people would assume is correct (stop assuming the longest date ranges), or give the user the option to operate in one mode or the other. This latter approach I think would be best as it would account for the above issues without removing any existing functionality.
Just a thought.