I think your whimping out on the amount your applying and working yourself to death.
Load it on and knock it down.
So many think "I just need to fill this low spot but don't realize that low spot is MUCH larger and end up sanding,apply,sanding,apply,etc.
That and being chincy on the cost of the product.
"Man this stuff costs,so I'll only use what I need."
That thinking will work you to death as well.
Forget the cost and slap it on. YOu'll sand most of it off once instead of the same amount MANY times. Make the dust once or 10.
I personally try to metal finish as much as my ability will allow and this goes a long way without using much filler. I just did a lot of patch work which shrunk of course due to welding and because there was no getting to the backside,I used a stud gun and worked the patchs back up. 1 pass with Rage and a skim of Metal Glaze and I'm done. Course,I hammered the Rage on so I'll have enough to level it out cause,
1. I was not concerned with the "cost"
2. I wanter enough to NOT have to go back over it.