Good point. I should have realized that. I didn't even think about it because I've had several android apps that have managed to incorporate these options, such as time since widget . I'm not sure how it works though. I can see how a months option would be more complicated.
I'm not a programmer, but at least with a years option is it not just the case of setting your start date, September 28, 2016 for example, and then years are reached whenever September 28 comes around again? The only way I could potentially see a problem is if somebody sets the start date as Feb 29th on a leap year. If it isn't as convenient as that, maybe just make a year 365.25 days or require 366 days needed every leap or 4 years. I can't imagine people using the stopwatch for similar reasons as me being too upset about it being off by a couple of hours for having a year setting. I can understand the desire for other people and Anuko to have it as accurate as possible though.