I'd point out that in #1, you aren't shooting for a 100% strength in the entire system.
you would still want to go for a 50/50 (thereabout) solution. I think Tony is stating to pour full strength in to RAISE the overall strength. If you add 50/50 in there, you are only maintaining the overall solution strength while raising the level.
In no way should you run 100% coolant in your system.
Ray