Are you looking at the total amount of power being drained from the battery, or the percentage of the top apps in the list? The total list will always be 100%, regardless of how much power is being used, since it's showing which app is drawing what percentage of the total amount of power being drawn. Even if the battery lasts 5 days, the bars will always add up to 100% (or would if every single app that woke up for a milisecond was shown).
The amount of power being drawn is going to vary by the strength of the 2G signal you're receiving (even if you're not using data), if by nothing else. And that changes as the trees move, airplanes fly overhead and cars pass your house. The only place you can come close to getting the battery use consistent is to put the phone and a nanocell in a screen room and keep the door closed, so no outside factors influence the phone.
As far as task managers, those things that kill apps, they cause more battery use, they don't save any. The concept was designed by someone who thought that Android works like Windows - it doesn't.
If you get 2 days out of the battery with the phone just lying there doing nothing, you're getting normal life from the battery. You're using Greenify, so hybernate anything you don't need to be awake - phone, email, text - what we call asynchronous apps, those that have to work when you aren't telling them to. And keep anything you're not using off - wifi, GPS, Bluetooth. I run a smart Wifi app, only because I forget to turn wifi off when I leave the house, so the net is saving me some battery, but if your memory has fewer holes than mine, don't even waste battery on an app like that.
Don't bother reinstalling apps - an app draws what it draws, it doesn't start drawing more current because it's been in the phone a long time. You'll just waste a little time and a little battery doing it. (And if you somehow lose that picture you didn't back up, can never take again, and it's a memory you never want to forget, you'll hate yourself.)
