It's relatively safe to do so for a one-time bulk load, especially if you have a way to verify consistency what you've loaded for integrity reasons (foreign keys, for example, might be a single query and a join). If it's not a one-time load, then you are right, it's dreadful.

If, for example, you get a 3-5x speedup without checks (not unheard of), you can do it twice, verify the copies are the same, and get a 2x speedup.