I would like to speak in defense of Hanon. I warm up with Hanon for 30-40 minutes every day. Since I was introduced to Hanon six years ago, it has helped my technique improve by leaps and bounds. I do believe it ineffective ONLY if one does not do it consistently. If Hanon becomes a part of one's everyday practice, though, the change is indeed noticeable and beneficial.
I was wondering - when you sit down to practice at the piano, how many of you do warm up scales or exercises? I usually just plunge straight into playing. I know scales increase your technique and dexterity but I don't practice them at all unless I have to (like for an exam or something). What do you guys do?