Naps 💤 & wake times 🤗

Does anyone know where the estimated wake times based on baby’s age come from? I’ve read that they’re “averages” or estimates, but beyond that...where in the world did these numbers come from?
I’m having the hardest time convincing my husband and my in-laws that our almost 6 month old needs to nap every 2-2.5 hours. They think I’m nuts for putting him to sleep that often and I’m finding it hard not to be bothered by their doubting, questioning, and judgement. In particular, my husband (who is medically trained) seriously doubts the legitimacy of the sleep studies that are cited in all the sleep books. I hear him, but I also find it to be true that our baby does in fact do better during the day when he’s had 3 naps! (Especially because his naps are typically only 30 minutes each, although sometimes he’ll sleep for 1.5 hours for his mid-day nap.)
Anyone else dealing with a similar issue, or can shed some light on where this info comes from so I can end this debate? My MIL was offended the last time they came to visit (they live in the same city as us) and I put our son to bed a couple hours after they got to our place. 🙄  She just doesn’t get it because the focus on sleep wasn’t a thing when her generation was raising babies.