I haven't read the previous posts because wow 4 pages! But I wanted to chime in with my opinions.
We also just fall asleep when we fall asleep, but my son is only 10 months which is totally different then a 3 or 5 year old. When he is tired he gets fussy and grumpy and I know he wants to be held and/or nursed, then he falls asleep. I very very rarly work at putting him to sleep. If it takes more than 10 mintues and he odviously isn't interested, ie trying to crawl, screaming/crying when I try to lay him down or nurse him. He usually plays himself out and I snuggle him then put him to sleep.
I think it also takes knowing your child and know what helps to fall asleep/stay asleep. Some nights when I am exhausted and I know he is too, but he won't lay down I have to go into the computer room and rock him. I think it's a combination of the heat, the light and the humm of the 3 computers. Other nights he wants to be laid down and not touched, or he wants to lay down but be snuggled. Just like everything else in child rearing you have to learn their signals and learn what to do with them.
Some kids need schedules to function, especially many high needs children. My stepmom's sisters son is extremely intense, he has some autistic tendancies but not diagnosed autistic. He is extremely intense. He has to have a shedule. He was ask what time it is so he knows when it is time to go to bed, take a bath, read a book, etc. He thrives off it. If you tell him you are going to be a little late leaving for school, he freaks out.
On the other hand I have a friend who is very schedule orientated. At about 1 month old she started her daughter on a schedule for sleeping, bathing, nurseing, etc. When she started solids at 4 months, she ate them at a specified time. The sad thing about this was that the mother unknowingly helped to pretty much wean her daughter. At 12 months she only nursed her in the morning and at night. I am not knocking her because it is very cool that she is still nursing, but there have been times when her daughter wants to nurse at play group because other babies are, but her mother tells her "No, it's not time for bed, you can't nurse yet."
I personaly don't like schedules, I had a hard time waking up for school my whole life no matter what time I went to bed. I am just not an early riser, never have been. So, we go to bed when we are tired and wake up when we wake up. But I think we will have trouble when DS gets to school age because he can't just go whenever. He needs to be there on time, etc. So I feel around age 4 or 5 I will try and get us on a more regular schedule for eatting, sleeping, baths, etc.
I say whatever works for the family. I don't think every child needs to be on a schedule or doesn't need to be on one.