Just curious, what's a normal amount of screen on time from a full charge until empty for the n5 with 4.4.4 kit Kat?
First, "until empty" will give you about 6 months of battery life - which is especially bad for a phone that doesn't have a user-replaceable battery.
Second, the screen is one of the largest consumers of battery power. Two or more days of standby should be about all you'll get under anything but laboratory conditions. (Put the phone in your pocket and the signal gets weaker, so the transmitter power goes up to compensate, using more battery - even though you're not using the phone.) Add a few hours of screen on time and that's the end of most of your charge.
Charge at 40% to 50% charge left, to maximize battery life. If you need more, with that phone, carry an external battery (look on Amazon) or stay close to an outlet. If you need a lot of time between charges, make sure your next phone has a replaceable battery. Buy a spare with a dual charger, so you can swap batteries at the 40% point, then charge them both at the same time (one in the phone, one out of it). Or you can carry 2 spares. Or 3. Or as many as you need. (Chargers for th battery out of the phone are about $5.)