The demands of a heavy deadlift are different than a high rep deadlift. If you brace every rep on a set of 12, it’s going to take you a minute and a half to finish the set. Plus, you’re spiking your blood pressure more than you need to.
A way to think about it: use as much as you need. Don’t lift 45lbs like it’s 405lbs.
Here are a few videos where I talk through more of the differences.