Pebble, when I'm wondering whether I'm approaching a situation in the right way - i.e., am I approaching it the way that suits me, or that suits my daughter? - I think, would this be appropriate for a second child? And if it would be, I carry on.
With a second child, you already have a schedule, and they have to fit in. They learn to be adaptable. You're more lax about telly, about food, and second children grow up fine, well adjusted adults, so it can't matter, you know?
FWIW, I have one. 20 months now. And as a younger baby she was unusually adaptable, I think - we went with the flow, she went with the flow, we genuinely were that couple who said "oh we just carry on with our life she fits in". We could take her to a party and she'd be awake and happy till 10pm, and then we'd change her into night nappy and PJs, drive her home, put her in her cot, lovely. The rest of the time, she napped when we gave her the chance (like, in the car), we changed our plans on the spur of the moment because she'd fallen asleep in the car, we all spent a year plus just making it up and it was fine and great and wonderful.
At around 14 months, that changed. She went to bed at 7.30pm, and she needed a routine. At 20 months, she is expending so so so much mental energy learning the world, that she needs some things to be predictable and routine. If I play a game with her two days running at a certain time, she expects it every time from there on in. That's a long way away from you, but I'm mentioning it because it fits in with my whole long post.
Which is this: they will tell you what they want. If you are fine without a routine, you're fine. If you're all happy, don't change anything. If your children suddenly need a routine, trust me, they will let me know.