In ~95% of declared emergencies, there is zero paperwork or followup required. In over half of them, the pilot elected to (voluntarily but advisedly) fill out a NASA ASRS form (which is about a 15 minute task and something they probably would have done under the same circumstances without the emergency declaration). ( https://asrs.arc.nasa.gov/docs/ASRS_ProgramBriefing.pdf )
It may be that training pilots specifically to declare emergency as soon as there's a problem rather than waiting until they're sure they can't solve the problem and need outside assistance will improve overall safety outcomes.
There's a tragic case I watched a safety video about where the private pilot, very low on fuel, asks if he can land at a (closed) airbase whose traffic controller he's talking to. The base's controller says he cannot land unless he's an emergency. That was his last chance to survive, all he needs to do is say he's an emergency - "I'm on fumes, I need to land right now" she'd turn the base's lights on, he puts it down on a strip that's not meant for civilians and maybe he spends the evening explaining to some MPs how he fucked up - but he's not dead. Instead he accepts this as a "No" and flies on for a few more miles until he runs out of fuel and crashes.
PS1: I saw what I think is that same ASF video ( https://youtu.be/fLlWf-Fk_YM?t=10m ). Really frustrating, especially how obvious it was an emergency to everyone except the two people on the radio (where the bulk of blame belongs to the pilot of N4975S.
PS2: One of my instructors was in CAPS Event #59. I talked to her afterwards; she was a fan. :)
Calling them all "saves" is overstating the incremental benefit.
Declaring an emergency (standing alone) should not be a reason to pull the CVR, IMO. There should be an aviation-safety related reason at a minimum. (Declaring an emergency to facilitate expedited handling for a passenger medical emergency should not trigger a need to preserve the CVR recordings, as one concrete example.)