A question about chip loads.

Hey guys.
On Monday I will be going back to the Job I started Friday.
After turning and finishing I will thread. OD.
Then I will mill out 2 key ways.

This is where the question come in...

The primary key way is .375 wide by .200 deep.
The material is 4140 HT.
My tool is a 3/8 solid carbide EM 4 flute.

I did my first article on Friday, taking .05 doc. Passes. 4 in total.
Chip load per tooth was .0015. It ran nicely.

But 4 passes seems like too many. So I wanted to try a single pass.
But when I type in the numbers for .200 deep. The suggested feed rate makes the chip load .0006 per tooth.

This worries me. Because won't I just rub the EM to death?
I've been told that it's better to take a bit of a bite into the material so you actually cut In to it vs just rubbing it.

So I was thinking two passes .100 doc each. That puts the IPT at .0011
Does that sound better or should I just go for the single pass?

Not sure about the whole rubbing the EM to death. Not even sure if that's true.

But it's what I was told.

Thanks.