In regards to life of a coil, it is relative to the person using it, the liquid used and the power supplied, good maintenance also will elongate life. So to say a coil will last 3 days may be a week for another based on those factors.
As for the power chart...it is for giving a
general range of effectiveness not the gospel by any means and is more for basic low end coils than for a RBA or RDA style or other more advanced coils/carts. Just use it to start the ball rolling then adjust up until the "sweet spot" is achieved. But to set a power level with the ohms in the coil per the chart may not give the result expected, again it is only a reference but not accurate.
This has been stated many times but I will say it again, the best way to find the desired result is to start on low power and incrementally increase power until the desired result is achieved, this is a very fail safe method as you will not over power the coil and get a bad result.
But to set a power level according to a suggestion made, may not work as it is again dependent upon the users style of vaping and the juices used, battery type etc. 15 watts for some may be too much and yet not enough for others so the best is to start low, increase and find "your" spot.
