For anyone who has any success with Hasty Handing leves, what kind of exp are you getting per synth?

Is there a method you need to follow? For instance at rank 40 would I want to be doing all r35 leves for best chance at success? Already you're taking an exp hit, nevermind the fact that you are getting half exp for Hasty Hand.

I just don't see how this works, unless you take into account that it's free exp (even if it's 100-200 at a time) pretty fast.

I have 99 leves stored up and am considering trying this since I was a bone head and didn't synth a bunch of lumber pre 1.19.