Is the book opening chests faster worth it? Short answer, no.
Long answer:
The 3 day book (best budget) costs the equivalent of 16,000 gold. In 3 days you open 2x the usual number of chests. So the calculus is, does opening chests on average normally net 8,000 gold in gear etc over 3 days?
3 hour chest
31 cards = 155 gold
102-123 gold = 112 gold
Total = 267 gold
8 hour chest
69 commons = 345 gold
8 rares = 400 gold
256-307 gold = 281 gold
1026 gold
So in 11 hours, assuming regular chests, one earns 1300 gold. Over 3 days, that’s about 8,000 gold. A clan mate noted that you’d need 16, not 8k. So totally not worth it.
So, yes, it could be worth it, if you get way above minimum chests. Like several 12, 18, or 24 hour chests. Or if you get lucky in what’s in those 3 and 8 hour chest.
But yes, it’s like getting a free 64 gems… but no it is not.
Because you end up with a LOT of useless cards that you have no control over, not even control over whether you can sell or donate them.