Coils last a different amount of time for each person as it depends on the liquid used, the amount of sweetener in it and the pg/vg ratio amongst other things. Everyone draws slightly differently a slow gradual draw is recommended to pull a consistent amount of liquid into the coil. If you use your vape all day everyday then a coil should last you two to four weeks but this is very much device and liquid dependant. Heavy users may be changing coils every week. Check your coils recommended wattage range Running too low or too high can cause a coil to perish quicker.