Squishiness can be a very important factor in O-ring and also if the manual says replace at a certain frequency there is most likely a reason. The flattest O-rings I see are on vaporizer connections to the anesthesia machine.
What is the name of what you put on your O-rings? I'm getting a bunch of computer cryptography stuff rather than anything you put on O-rings. Krytox? Crytox? Cryox? Coming from the HVAC and Automotive industry I usually use a silicone lube so I'd love to know other application specific stuff.