I started out reading Wake Up To Your Life, built up to doing about an hour a day, went on a retreat[1] run by the author of that book, from which I saw huge benefits, started meditating for really long stretches in order to hammer home the skills I'd learned there, then settled down to an hour after rising and an hour before bed. (Plus any time it's useful during the day.)

[1] Recordings of the talks at that retreat are linked from this URL: http://unfetteredmind.org/audio/podretreat.php?code=PAP#here They're the PAP01-PAP10 links.

If you do vipassana via http://www.dhamma.org/ the ideal daily sitting schedule in day to day life is an hour in the morning and an hour in the evening. If you make it part of your routine, it can be somewhat easy to do. It's actually trivial to be on the 2 hr/day schedule after finishing a 10 day sitting since 2 hours is nothing at that point and you remember exactly what you're doing, but in my experience it's difficult to start up again with regular 2 hr/day sittings once you stop. My routine for a bunch of years was to do the 2 hour sittings for a while, but eventually fall off until going to another 10 day sitting.

Even though 2 hours seems like a lot, because of what it is (focusing the mind, learning to not overreact to external stimuli, stability of the mind), it makes people able to be very highly productive throughout the day.

I've sat for 30min a day since Jan, & I get a similar 'regulation' effect. YMMV