For my son, a schedule was absolutely necessary for his well being. I think around 5 months is when we really fell into a solid nap/eating/outing schedule, and at that point he was taking 3 naps a day. I followed his lead, but started paying very close attention to when he showed sleepy signs and would put him down for a nap as soon as I noticed he was tired. At that age, he would fall back asleep within 1-2 hours of first waking, then take another nap 2-3 hours after he woke, and another 3 or so hours after he awoke from his second nap. This meant I had to really be careful and couldn't just leave the house whenever, because he needed to be home to take a good nap. He was never a fall asleep in the car seat kind of baby. So I made sure our outings were quick at that age and always had him home, well fed, and comfy by the time he was ready for sleep.
But it's also relevant to mention that I held my son for every.single.nap from 4 months to 11 months. Around 4 months he stopped sleeping on his own, and if I put him down for a nap, he would wake within 30 minutes and be super cranky/fussy and overtired, then not nap well the next time. The only thing I found that worked (and I tried EVERYTHING) was holding him for his entire nap. I would get comfy in my recliner with a book and some crochet and my computer, and settle in for his nap time, or nap with him. It worked for me, and I credit the fact that I held him for all those naps as to why he's such a good sleeper now (he started STTN for 11-12 hours at 13 months and still goes down for 2 naps a day, very easily, without much assistance from me anymore). At least I think that's partly the reason he's such a good sleeper! And I know a lot of toddlers who never had good nap schedules and are now really, really difficult to put down for naps. I'm a huge advocate of instigating a flexible, baby-led schedule, and really think it helped my son