It's never "ok" to sit on the break. It's not like there's a rule book for these things, and everyone's best interest is different. The problem is the question is wrong. The real dynamic is one should only work as much as it benefits them, without getting them dropped. Keeping in mind that the them includes their teammates also in the break. Soooo if you have teammates in the break and you're just hanging on and annoying other guys in the break you're likely slowing them down. Depending on the complex algorithm of who is there with what numbers and likely to win, a weak teammate is probably best served burying themselves to give the break the best chance of survival.
If one is alone their sole goal is to survive so sitting on when tied makes sense, Getting dropped certainly doesn't serve them. But the others won't like that, so they'll try and drop you or ride you off. Which can, in cases, cost you more energy than if you worked.
Like FF pointed out, this stuff is complex, and rarely functions well at the cat 4 level. It's about learning the dynamics of your abilities and riding with these immediately formed and quickly changing alliances/rivalries.