BeerBorg

Pretty much all the stuff the others said but for me since the recipe design and notes are on BB2's 'puter I have to make sure he adds notes when something on brew day changes.
Also since he puts the notes in I can't understand most of them and make him go back in and clarify. Then he puts them on the cloud so I can see them.

Seriously though I agree with John about taking notes about mistakes and how/what you do as an adjustment while brewing. You won't taste the result for a long time so being able to refer to notes at tasting time is a big help.

If something odd happens it is a lot easier to fins and resolve or find a pattern of issues over time and correct them. On brew day you just have to adjust on the fly and keep on going.
You can't try to trouble on the spot during a hot break for example.

I think brew notes should be like a diary where you put down anything that comes to you at the time as long as you actually go back and read it. That is a part of note taking that allows you to get creative and might trigger further research a day or so down the road.

Notes are good.