My wife and I bought these pillows when we purchased a King mattress. We have not had to make any adjustments to the fill. My wife is petite and I am not. In fact I use a CPAP mask. She sleeps on her side and stomach, I am a side and back sleeper. All are neck aches and pains have gone. I used to used to have to sleep with a neck pillow on top of my pillow to keep the mask from falling off. No more. The pillow did seem too firm the first night , but by the morning we were both hooked. Thanks for the great product. 
P.S.
We have had the pillows for 30 days.