Pheryll
Set Designer
Even if you ignore the Spell Fragments (as the values have changed since the above post was made)... 24 years to upgrade all Ancient Wonders? Obviously this means the developers do not intend players to build all 40 AWs. So what do they intend? How many Ancient Wonders do they expect the "average" player to have? Do they intend for players to have only two or three? Maybe four or five? Do they intend for players to mostly upgrade their Wonders to level 10 or maybe 16 at most (note they point out that this is 75% of the power of max level), and intend for levels 20+ to be "expert" levels that require a lot of time and effort to get to that only the most hardcore players (and/or those willing to spend Diamonds) would ever achieve?
My estimate is that at late chapters a casual free player would be able to upgrade 1 wonder to level 16-21 in the time it took to move through the chapter (this estimate was made before the announcement of the decreased SF). Thus I would assume that at end game free casual players might reasonably have half the wonders moderately leveled.