I've always just followed by child's signals.
Babies - like all humans - are quite routined creatures. They don't work to the clock though.
For example most people generally get hungry at lunchtime, because we are creatures of routine. But depending on what you ate earlier, how much you ate, how you're feeling, how knackered you are - these all affect whether you eat lunch at 12pm it 2pm and if you eat tons or not much.
Likewise bedtime. I'll generally go to sleep in the late evening and wake in the morning. Because humans are naturally routined like that. What time in the late evening I go to sleep and what time in the morning depends on many things - how much I slept the last few days, how I'm feeling, how busy I've been, what type of activities I've been doing (in front of a screen, exercise, watching tv, reading).
Babies are humans.
Of course they like routine and structure. But that needs to be flexible to fit in with the differences in life.
So as long as you follow babies lead and can know (and often predict) their signs - then being flexible with when dinner is and what time nap time is is fine and normal. As long as dinner and nap time happen as needed. Expecting that a child will thrive on chaotic no-structure though is a bit unrealistic.