I haven’t calculated.
I’m simply saying, what’s the least possible number of generations necessary to see a new feature.
If we think this is hundreds of thousands of generations, say 100 to 200 thousand, but mammals have only been around for 1,000 generations, then there has not been enough time.
It's evolution; things are in constant flux.
You're not going to be able to see a "new feature", since whatever you're looking at has been making slow incremental changes over millions of years.
Biology doesn't work like an assembly line.