You seem to be dividing into traditional 401k and taxable brokerage, but Roth can be an important piece of your puzzle, as can IRA, both traditional and Roth.
If someone is going to retire that early, they will likely be able to take advantage of the Roth conversion ladder while still controlling taxes. As such, they need enough in taxable + Roth contributions to get them through the first five years.
If you are in a particularly high tax bracket now, then it may even be advantageous to take a tax deduction now, then pay a much lower tax rate + the 10% penalty in early retirement.
As you can see there is no general rule of thumb split, as the results depend a lot on your own spending. However, the general order of investments still applies in most cases. Don't give up on tax deferred space out of some misguided understanding that you can't touch those funds until a certain age.
We likely will not meet our original taxable goals because we found out about the mega backdoor Roth, so now we have an extra ~$30k each year going into Roth, along with all of its growth over the last few years.