I used to use both...laptop for quick typing, and then the iPad for hand-written notes or annotation.

The OneNote app sync is quick enough that I could type lecture notes on the laptop, and then quickly switch to the same document on my iPad to sketch out a diagram. It was overkill for sure, but very useful

I mean at this point with the latest ones, an iPad Pro with it's keyboard/trackpad accessory and a pencil could probably manage both for you pretty damn well.

I just wish they'd let us run MacOS on iPads.