Here's my good old 2012 Nexus 7, still on Android 4.1.2, with over 2450 hours of system uptime (no reboots)
I reboot my tablet after every charge. Here's why: A portable device should be turned off while charging. This allows the battery to reach the threshold voltage unhindered and reflects the correct saturation current responsible to terminate the charge. A parasitic load confuses the charger. (Battery University)
So, 780 hours is my max so far