Isn't mobile more like 15W though?

Depends on the definition of mobile I guess.

I've got a T470P (i7-7700hq), that's a 45W part in a 14" laptop.

If I balls to the wall it I can kill the battery in 90 minutes (though they are swappable) but I average ~6 hours under actual work conditions (VMs and Intelligent).

It spends the vast majority of time sat at a few percent utilisation but the processing power is there for those few second operations you run infrequently (build from scratch, indexing a large project etc).

I love it frankly, not turned desktop on at home more than once or twice since July.