Yes, leggo books are really valuable for me still. But here's the thing: I'm really low on gems. Under 1k. Even to the point where I now stopped farming IT on weekdays until I'm back up at 2-3k.
14k champ training with t2 stone + leggo book have become the standard. That's worth spending energy on. Then there's all the special events that pop up lately between fusions. Those can be really high value. And I just joined a T6 clan that demands I run a bunch of spider 10h every 2 weeks. There also were the two DDs with lots of oil, that was a massive energy drain. Honestly I don't know how you guys do it. I have a very very hard time keeping my net gem flow above 0 unless I buy daily gem pack.
About this DD being "triple dipping":
I can either run dragon 10h, or dragon 25 with food. The value of the latter has dropped a lot now that even 6* epic gear is sold without rolling. I have to discount the gear almost entirely. Also, I'm at 8k champ training (all in 12-3, no brews) and only 1400 DD points. Even if I maxed out dragon tourney, I'd still be about 2k energy short of the leggo book. So I stick to my initial statement that it's just bad value.
Btw, I just watched a video by Eharbad today where he complains about the state of the game and the massive stat inflation. For me this hasn't been a bad thing, as it's allowing me to catch up really fast to older accounts that spent years farming stage 25. But in that process I have radically shifted my valuation of gear. With blessings and oils, dungeons aren't even that key to high stats anymore. Which is why I try to only run 10h (and 4h FK sigh). Anything below 6* leggo is questionable these days.