Due to the unique shape and sizes of the particles in Arctic Silver 5's conductive matrix, it will take a up to 200 hours and several thermal cycles to achieve maximum particle to particle thermal conduction and for the heatsink to CPU interface to reach maximum conductivity.
So by my estimation of this statement it would take almost a year of normal use to properly cure the AS5 compound, or almost nine days of continuous power cycles to meet their recommendation. Benchmark Reviews feels that this is a characteristically unreasonable requirement for any TIM product, and we do not support it. We want products that perform without the burden of sacrifice on our time, especially with some many competing products offering performance without this extra requirement.
Shin Etsu is less than half the price, has same thermal performance as AS5 and has no curing issues.