Your collection is a live thing, not a list
Your collection is alive.
The moment you write a number next to a pair, it starts going stale.
The moment you write a number next to a pair, it starts going stale. Resale prices move — daily, sometimes faster — which means a value you calculated once and never revisited isn't wrong exactly, it's just describing a market that no longer exists.
CYKI's pair values and collection total aren't a one-time entry; they're read from the current market each time you open the app. That includes what condition does to a graded pair's value, and it feeds all the way up to the collection total, not just the individual pair's own card. A rack you catalogued in June and a rack you catalogued yesterday get treated identically — priced against today, not against whenever you happened to type it in.
The same idea scales up to the whole market: the CYKI 100 is a living index, not a fixed snapshot, precisely so a collection can be measured against something moving at the same pace it is.
It also means two collectors who catalogued the identical pair on different days should never expect to see different numbers just because of when they happened to look — both are reading the same live market, not each other's snapshot from whenever they last opened the app.