I agree with the others that suggest practice in learning the rig, but adding a restrictor valve is a solution as well.
Part of becoming an operator is learning the 'feel' of your rig. Yes, that moments inattention can cause problems, but that's also why you need to be on your A game when doing work with 2000+ PSI hydraulics! You can't be distracted by other things when working a hoe or loader or anything!
Try to find a feel for the machine and train your hands to know that feel. With practice, it will become easy and you will have no need for mechanical items to develop the feel for you, thus you never will.
When worked properly, a backhoe operators hands look like a conductors in an symphony. Subtle movements, smooth, agile and the orchestra (hoe) follows beautifully....
Here's a beginner that has been given some pointers by a pro operator. If you watch his hands, they barely move as he practices.
https://www.youtube.com/watch?v=Koa56PuOYOQ
That's proper for practice operations. With enough practice, you'll be able to actually control the acceleration of the components, start, speed up, slow down, etc. You'll lose less material doing this and become pretty quick. With a restrictor, you'll only have a top speed of whatever you set.