It all depends on demand. In the vintage sports card world, the increase is astronomical because everyone on the planet wants a PSA 10 1952 Mickey Mantle and there exist very few. Obviously, the number of people who care enough about a tan-back Lavirus is much smaller. A PSA 10 Band-Ache White Back would definitely break the bank. It's largely a function of the profile of the card driving demand.
I would add: in sports cards, so many cards have been submitted to PSA that the population reports are meaningful. There are many BB card with endemically bad centering and they are legitimately rare in high grade as a result. There are a few wackys that fit that description also (Sweathard, 8-Lives, etc.) Garden variety wackys are hardly worth submitting to PSA. As a result, there could be some wackys here and there for which a PSA 8 doesn't exist. That doesn't mean they're rare or should command a premium. It just means no one has bothered to submit them yet. The whole "Population 1" justification for charging huge bucks for a graden variety wacky is logically flawed, but once in a while I guess you might convince a rich, uneducated registry collector.