A while back i stumbled upon one of the new additions to mooglebox.com, a site with
"gathering information". Content was new to me and really interesting, that any item you can mine/log has a specific remainder bar length and strike zone. I've tried it out during the last week while doing the G1 & G2 achievements for mining, and i have to say, it works really well.
One thing that has to be noted (it's mentioned on the MB page, but i want to repeat it here) is that it only works when your level and class-relevant stats are above the grade you are working with, otherwise the items will just hop between random spots.
With this knowledge you can put something together that i'd call a "grade thumbprint" (hey, i'm not native english and couldn't come up with a better name

) for a certain area. I'll use the letter/number scheme that MB also uses.
So, for example, the "thumbprint" for the grade 2 mining spots around Emerald moss would be:
A: strike zone 2 -> raw sunstone, raw malachite
C: 2 -> zinc ore, minium
D: 3 -> silex
For G3 (Tranquil) it is
A: 2 -> raw garnet/peridot
C: 2 -> silver/zinc ore
C: 3 -> alumen
That way it gets really easy to predict what item you get and where on the gauge you have to hit in order to obtain it. Can speed things up quite a bit when you don't have to "search" the strike zones for the right spot

Big thanks to Jet Chan (the one running mooglebox) and Aviha Chai for getting all this info together! And i hope some of you will find it useful as well ^^