hobnobsaremyfave :
I let DS1 "find his own routine" until he was 18 months old. The lack of sleep and chaos that ensued...
I think it depends on your baby, surely?
I let my dd find her own routine, and it worked brilliantly. By 4 weeks old she was feeding every 4 hours during the day, with pretty much constant feeding from around 7.00pm until about midnight, at which point she would doze off and sleep until 7.00am. Once weaned, I sort of imposed routine - I offered her breakfast food at breakfast time, and lunch-type food at lunchtime etc, but even these mealtimes were a fairly movable feast depending on what i was doing (mornings when I worked, it was a bit later for example).
I think that each baby is an individual. Some babies quickly settle into a routine of their own making. I did everything 'by the baby' instead of 'by the book' and it all fell into place for us. I had a happy, contented and placid baby who was a joy to be with. Other babies just don't operate like that.
I also think it changes with age. I started imposing a routine (of sorts) as I was weaning - I offered breakfast food at breakfast time, lunch food at lunch time etc! I tend to put her to bed at around the same time each night, and I tend to give her a bath first so she knows what is coming next.
I think there tends to be a tendency to polarise a bit too much. 'Routine' tends to invoke images of a terrifyingly strict, clock-watching mother, refusing to pick up her baby except at specified times, and lack of routine implies chaos and a mother who cannot see past her own infant. I don't think either extreme is especially helpful - you can do things differently as a baby grows, adjusting to their needs and gradually adjusting them to the needs of the wider family as they grow. You can do some routine but not be rigid about it.
Most of all, I think it is important that you find a way that works for you and keeps your baby happy. I don't think that a baby who screams for an hour or more can be said to be happy and that, to my mind, needs looking at. That baby is simply learning that when something is wrong, no-one comes to help as the baby has no concept of time. 10 minutes, because the baby is tired and yet unable to settle? I never let mine cry, at least not until she was 10 months and we did controlled crying to teach her how to settle herself to sleep (she liked to go to sleep on us, but was easy to put down after she'd dozed off), but I don't think it would cause lasting damage.
Ultimately, people have to get to know their own children and figure out the way that works best for them and their babies. And usually, most of us fit somewhere in the middle rather than at polar ends of the spectrum.