I love my warm up! mainly because i have to be quite particular and it puts me in the mindset:
Start with Stretches, massageing my wrist to fingertips, and then stretch fingers, wrist shouldes using known practices.
Then its scales, arpegios,broken chords for 15-20 minutes or more.
then sight reading.
This lasts around 30 mins.
I tend to not go through excercises like hanon at the moment as i have injured my little finger and i dont want to overstrain, but they are good for technique but no more than 5 minutes to avoid bustin urself up if you tend to get to into it.

(from my experience) i tend to use them as a means to play while working on technique and stopping tension.