[Update 2: 72 hours!]
[Update: It's now more than 48 hours!]
More than 24 hours ago I started the test to find out how long my project would run on a CR2032 coin cell battery (More info about the project here). Thankfully, it is still running with still a lot of power left.
Of course, 24 hours is not a lot, especially for a watch, but it is a big deal because the project that inspired me only run for around 10-11 hours. Plus, my initial pen and paper calculations based on the current drain was around 5-6 hours.
Before this test started I measured the voltage at around 3.17 Volts. Now it's at 2.97 Volts and it seems that the optimizations backed by my research is paying off. I'll continue to run this test until the battery dies out. Will make another log to summarize my findings.