Clearly the amount of hours you wear your headphones is a more accurate method of measuring ear pad usage. Because my HD650's were my "go to" headphones I'm estimating that on average I used them roughly 1 hour per day which translates to about 1,100 hours over the 3 years. Because I listened to them so consistently over several years I suspect I didn't notice the gradual deterioration in sound caused by the wearing of the pads. It's like you don't notice the dimming of your TV picture over the years even though that is exactly what is happening. Even after visually comparing the condition of my 3 year old pads with the brand new HD6XX pads I wouldn't have guessed that I needed new pads for the HD650's. However after switching the pads I realized that the old pads gave the headphones kind of a dull sound and with the new pads there was better clarity.