Honestly the frustrating part of breaches in maps isn't that you have to clear fast it's that there's not enough shit to clear - breaches would constantly be in shit locations where there just couldn't be that many enemies, or in good locations where inexplicably few would appear. I don't think I'd ever felt limited by my clear speed dealing with breaches.
And breachstones were supposed to be the end game of it, I'd say it's okay to have a bit of it that requires some level of clear speed in your build.