This is a question I get very often and it's not easy to answer.
In general a coil head or clearomizer can last anwhere from 3 to 14 days.
I get many questions about which coil lasts the longest, but it's not really about the individual coil. Some coils will last longer than others but there is no way for anyone to pinpoint which one would last longer, for you.
A coil can have a short life or "die" for many reasons:
1. Votage used. If you use too high a voltage for the ohms of your coil you can burn it out, weaken the coil, burn the wick and cause it to die rather rapidly (sometimes instantly) Excess voltage will burn the enclosed wick on your coil, this causes excess heat build up because the coil canot get saturated with elqiuid and the heat is not dissapated and the coil "pops"
2. Chain vaping. Even if you are using the proper voltage, chain vaping (not taking time between vapes) can cause the coil to over heat, burn the wick and kill the coil.
3. Carmelization. Build up on wick is the most common issue in longevity. If you have a sugary liquid with sweetners in it, or a tobacco based liquid the sugars will carmelize when they encounter excess heat (the coil) these sugars are deposited on the wick and the coil building up, "gunk" stopping the wick process, ruining the flavor and the coil.
4. Liquid viscosity
If you are using a liquid with a high VG ratio the thicker liquid can impeed flow to the coil, causing the coil to heat up and prematurely die.
No matter how well you take care of a coil, clean it, avoid chain vape and use the right voltage, it will eventually die out and need to be replaced. If you find your coils not lasting very long it is generally something from the list above or a combination.
If you find yourself constantly changing coils, you might simply want to lower your voltages, increase the ohms of your clearomizer or coils or switch clearomizer type.
However, simply changing clearomizers isn't always the solution, sometimes it is but more often than not if you are experiencing short coil life it is something from the list.
In addition, coils are not all the same, sometimes wicks are different, coils are different, you will need to experiment to get the best clearomizer or coil for you.
Finally liquids being used. Liquid can damage plastic cartomizers, for a list see this ECF thread: