Each baby is different and some will adapt to it, others won't, same goes for the parents I'd say, some will find it easy, some will find it hard, some will find it doesn't work and others will. We decided to put a bedtime routine in place at 6 weeks because she was wanting to stay up all night and wasn't napping properly, she would then take hours (and I mean hours to get down), every time I tried to put her down she'd scream the house down and wouldn't go down until middnight, 2am on bad days. This all coincided with me reading that babies who are overtired have more trouble falling asleep.
I had one of those annoying emails come through with advice about a bedtime routine (claiming to get your baby to sleep in 7 nights) so we gave it a go.
We started bath, pj's, milk and bed. The first night it took 6 hours and it was painstaking. Constantly rocking, shhing, calming and feeding her. We tried again the second night and it took 5 hours. All in all it took her 5 days to get it and once she did the change in her was immediate. She regulated her own day time naps, sleeping for 2.5 hours in the morning and 2.5 in the afternoon, sometimes longer, subsequently she was able to sleep for 6 or 7 hours at once at night, she'd wake for a feed and sleep for another 5 hours. Our only problem was that she wouldn't sleep in her crib in the daytime, only in the car seat/travel system. So in effect this was all going smoothly from 7 weeks, then at 9 weeks she started sleeping right through the night and going from 7pm-7am, we even had a night where she slept for 13 hours. She's 11 weeks tomorrow so granted I don't have a huge period of time to base this on.
At around 10 weeks she started feeding in great quantities at night time and getting quite fussy going to bed, so I assumed she was having some kind of crib aversion. DH works in a nursery and one of the girls he works with suggested maybe she was getting too used to the car seat. So we're currently in the process of trying to get her out of the car seat. I now realise that actually she's probably cluster feeding as she approaches the 3 month growth spurt, but being that I've been car seat weaning for 3 days now I'm not about to give in. What I will say is that taking her away from the car seat has thrown a MAJOR spanner in the works, she will only nap for 40 mins at a time in the crib, then in the afternoon not at all. So she's gone from 5 hours of napping during the day to less than 2 and she's waking up (just the once) again during the night at around 5am (and going back to sleep).
This tells me how much the routine made an impact on her life and how much she's got used to it. I feel like such a mean mummy but I might as well do it now or else it's only delaying the inevitable so for now I'm just going with the follow but keeping the bedtime routine every night, however much she wants to cluster feed.
I think the important thing to remember is that being a parent is hard work and you need to do what you need to do to get through it. It's quickly become apparent to me that just when you get one thing sorted something else comes along. No one really knows what they are doing, just look around on these forums for everyone asking for thoughts and advice. We're all just making it up as we go along, so why not give it a try, if it works it works, if it doesn't it doesn't. Good luck.