Just a comparison to last year:
Grand Bridge upgrade was available in one chest @680 florins with 20%. Statistically this meant that about 13600 florins were needed for the 4 needed upgrades
This year we will need 8 pieces from the chests for the full upgraded set. In the mean, the Chests have about a 10% chance for the special and cost about 200 florins - this leads to about 16000 needed florins (rough estimate). There are 16 more quests (about 2000 florins + 40 tickets more) than last year and quest rewards (at least of the earlier quests) give significantly more florins - also there are 3000 extra florins in the milestones and the event runs about 2 days (or even 3) days longer (48 more tickets).
Total florins to get (minimum):
7000 (26 quests x 250 + 500)
5500 (milestones)
6590 (if all tickets are used in the 100% game - 21day x 24 +135 from quests + 20 from milestone)
A total of about 19000 florins even without any gambling.
So statistically speaking it should be a lot easier to complete the set this time than it was to complete the bridge last time. Also I want to add that I had no trouble getting the needed upgrades last year - but maybe I was lucky.
Still, I also would like to see selection kits (for each building) instead of separate building and upgrade specials - because what sense does it make to gamble for the upgrade if it is not yet sure, that the basic building will be won.
Also, from a game theory point of view, everybody should only play the 5% game. Since it adds 15 florins to the pot, every ticket is worth 15 florins (+5 florins from the starting 100) instead of 10 florins with the 100% game or 10 florins (+7,5 from the starting 50) with the 15% game. But the payout is probably better distributed between players if only the 15% game is played...