There are other apps out there that do the same, but approach it differently. You have to find what works for you. No method is wrong in my opinion, it's just that you have to find the method that works best for you. ;-)
You're right. It's much more complex. Comparing happiness levels between work and non-work days was one way of trying to answer it. This method is still distorted by a lot of things, like you mention. I'm open for any different methods! If you have any ideas, I'd love to know :)
It takes me about 3 minutes every day to track happiness, and the advantages go much further than just the collection of data. It's also a moment of self-reflection and meditation in a way. It puts my mind at rest.
That's a nice idea, yes. If the happiness on non-work days is getting increasingly bigger compared to work days, at some point you should receive a bleep with "hey take some vacation will you?"