And I agree. The "3 Gk's per minute" is nothing more than something you should try to aim for. It's highly unrealistic to get 3 GKs per minute in Ravana Extreme Mode for example, but it's a a guideline of what is to be achieved during phases where you're standing still attacking a single target. Obviously, this "3 gk per minute" phrase doesn't apply when you're dealing with complex mechanics.
Always remember this. BOTD > GK. If it means you can only achieve 2 Gk's during that minute, it's better than letting BotD completely drop off. The only reason why BotD will ever fall off is because you blind-blew a GK without consideration before hand.
Having said that, there are also some phases in boss fights where it's even unwise to have BotD up or use its cooldown. Best example is Prelude to Liberation in Ravana EX. You'll have BotD available, but you shouldn't use it, as it's an 18s phase and now you'll be all in huffs and puffs because you don't have BotD up for Nagas. This is just one of the many unique examples I can think of, where it's better off holding BotD off all together, to keep it for another phase.
Talking of Nagas, due to the amount of tab-targetting required to kill the Butterflies, you can lose around 1 second per add you cycle through to attack. This will eat into your BotD time, meaning you will have to forget about blowing a GK until it's more comfortable. During that entire phase, I only use GK twice at a maximum, and I don't reapply BotD again. I try to juggle my current BotD timer, so I have my my CD ready for the next phase. I can use Ravana EX examples all day, but seriously, it's the best fight currently to illustrate how much you need to plan ahead whilst playing the Dragoon if you want maximum DPS.
This is exactly what I meant a few days ago. You can't blindly throw BotD and GK just because you feel like it. The Dragoon requires extremely precise pre-planning and coordinated movements during raids for maximum uptime. It's easily the hardest Job in the game to play as it requires the most thought process and knowledge of mechanics.