Welcome to RIU!
When I used GH Flora, I rarely ever had to go above 2/3 recommended dose. I've never used FF products though. You can always bump up nutrient levels if needed, but you can't extract nutes from the plant after over feeding.
What medium are you growing in? We've had a rash of new growers lately growing in FFOF soil (which is already infused with a month's worth of nutrients) with overfeeding issues because they then apply full dose of nutes on top. Don't fall into this trap. Understand your medium by thoroughly reading the ingredients and any information on the package. Ask here for clarifications.