Vape time and coil/wick quality depend on a lot of things.
Generally a lower resistance coil will run hotter and can potentially heat up the atomizer due to heat transfer, the device may become warm from that too. It's completely normal unless it's too hot to touch.
Chain vaping, or vaping with small intervals between drags will not hurt your coils as long as they stay saturated, the most that will happen is that the atomizer will get warm, so will the liquid its its a tank.
Wick usage time greatly depends on the type of liquid. Dark or sugary liquids will gunk up coils quicker and in return degrade vape performance over time.
I noticed that once I made the switch to unflavored I can have wicks last months. I have one RTA wick that is probably 6 months old or more, and it performs just fine and doesn't look bad at all, the coils are just a bit dark.