10gm per gallon wow that's really strong.
Depends.
It's pretty heavy for a soil grow... depends on your base soil of course. The MegaCrop feeding schedule tops out at 6. I'd think that they're publicly published feeding schedule would tend to lean toward the safe side. The same seems to be true with most lines of nutrients.
Traditionally, one kicks it up a notch until one sees sings that it's too much. Burned tips, curling... these are the major indicators that your Nitrogen is too high.
Now, having said that, I personally am at 10gr/gal and I'm gonna bump it up to 11 and beyond. Of course, I'm in a mostly neutral medium of Peat and Perlite with no significant contributions from the medium, so I have to feed more than those using soil.