Hiplock's (In my opinion) deceiving video. Link in this story.
That Hiplock looks like it's pretty hard to cut. But look closely. The disc cuts in partway, then suddenly wears down very fast, with clouds of dust. I think they are
twisting the grinder so that the disc wears down on the sides, not just the edge. Then the replacement discs are handled the same way.
Its seems that often, a manufacturer makes a "hard to cut" bike lock video, where they either aren't trying (I see ottolock took down their "failed to cut it with bolt cutters" video), or are using the
wrong technique.
I'm guessing it's about 90 seconds to make one cut on the hiplock. That's still a long time, with lots of noise. Does it require a second cut to pull the bike free? I don't know.
Try a diamond blade instead of the inexpensive cutoff wheels.
Like the lockpicking lawyer mentions, it's likely easier to cut the bike rack! Or the no parking sign, etc.