On the day/night balance, I was looking at cats as an example of a species that sleeps in smaller chunks and splits activity all around night and day.

Reading the article I thought there should be more weight given to behaviors different from sleep to adapt to the other niche, and also that being perfectly adapted to a niche doesn't sound like a benefit in the first place. My understanding is that most species have an evolution process slow enough that they never completely fit a niche but also have enough versatility to move around.

I'm thinking dogs, bears, crows, racoons, migratory birds etc. where adaptation happens, but not to a degree they can't move out from their niche.