BP gear box speeds are pretty close?

I started to pay more attention to speeds and feeds. I have been running speeds/feeds too fast.
On common materials the speeds on the head and the feeds on the gear box come close to calculations from the Machinery Handbook.

Was wondering if anybody has noticed this.

(I know it's a klunker, but after watching a documentary programs with Cubans driving those old Chevy's, I am not doing so bad).