Oily Dragon
Senior Master
You can spend a lot of time just breaking grips over and over and you'll definitely notice it takes a lot of work sometimes.Whenever I focus on breaking grips, assuming I even can break the grip, I feel like I spend more time and effort breaking the grip than my opponent does re-establishing it. For example, I break my opponent's grip on my lapel. He then grabs my lapel again. I've wasted energy for something he easily got back. And if we keep going, I've burned myself out and they still end up with the grip they wanted.
Often though, if it's taking a lot of "work" (as in energy you are expending), there's a good chance you're not using technique but trying to pull free, which if gis are involved is the whole point....if I get a solid grip on your gi lapel, your head and neck are now mine to move and you won't have the leverage you want. True "grip breaks" should be fast and decisive, and usually involve body weight rather than "pulling away".
A rule of thumb with grips then, is "don't let them get one". Because as soon as you have to break a grip, you're on the defensive unless you can use their grip. SO I agree with some of the others, that sometimes breaking the grip is warranted (if you can do it quickly), other times it might be better to utilize that person's tight grip on you, especially in an art where someone is trying to wrap you up in your own heavy gi.
Sacrifice throws are a good example, if someone has the Darth Vader death grip on you, they can become easier to throw.
A side note, grip fighting training is really hard on the hands. I recommend liniments/coolants/dit da jow for any training where your fingers get really sore. Many Judo and BJJ people learn this too late, and develop problems picking up pencils.