I got a few at the base 4500 on the practice mats without food. Could have been lucky and getting max seems a fair challenge. That's good, this is our "endgame", we shouldn't be figuring this out day one, so the more challenging the better. I like the concept behind it, adjusting your rotation as you go and being rewarded for smart decisions is a step in the right direction.
The things I'm not impressed with so far:
-Rng. You rely on getting enough good procs at good times.
-The Success Rate proc is not worth it. It only applies 25% to a handful of 50-60% abilities. One miss can wreck a craft. Again, even more rng. They could replace that or buff it.
-Older abilities weren't updated for the new procs. No making smart use of Intensive Synth, Tricks, Precise. Missed opportunity there.

But there's room to tweak and improve it and it's still early days, so I'll mess around before forming a solid opinion there.

The rewards and leader-board on the other hand are unfortunately exactly what I expected.
Correct me if I'm wrong, but currently I can't even find what the rewards are for ranking top on the 10-day leaderboard or how high a "high ranking" must be to be eligible. There are accumulated score prizes or achievement rewards that we can grind out in our own time, but that's a once-off.
As far as Skybuilder Scrips go, you get 60 for the regular grade 2 turn in and 76 for a near-perfect Expert turn in. Both give a kupo Stamp. So if you're grinding scrips, regular turn-ins with 3150 collectibility are miles easier.
Leaderboards are also quantity based, no real limits. Even if you don't max collectibility, you'll probably top if you play all day and spam enough. So more a time investment than skill.

Basically if you aren't interested in spamming collectibles for 10 days all day non-stop to rank on the leaderboard, Expert recipes aren't very useful except the one-time rewards. Our "endgame" is indeed a small piece of side content and now Master Recipes have been drastically simplified, that's it. We got put aside in a corner and told to spam collectibles all day for a vague leaderboard to keep us quiet.