I suspect there's an important psychological factor in the idea that the post its or cards are disposable while the paper in the notebook is bound in.

I had to work to learn to use my lab notebook for this kind of thing. In school I only recorded lab setup and results. Once I got a "real job" I realized (well it was sternly told to me) that even random calculations and stupid incomplete ideas could be very important to my employer at some point in the future if something related later came out. This included crossing things out in a way that was still legible.

When we'd sign each other's notebook pages nobody ever commented on the half-assed stuff in my notebook and I saw it in others' too.

> Once I got a "real job" I realized (well it was sternly told to me) that even random calculations and stupid incomplete ideas could be very important to my employer at some point in the future if something related later came out.

I got this lecture too, but (unfortunately?) all that really changed was that my post-it notes were stapled into my notebook.

I had to laugh, but technically, aren't you getting the best of both worlds?

I think you are as well but it does mean the person signing has to include a signature that spans both the post-it and the book's paper to show that the post-it wasn't put in later. Also it raises questions as to what is not getting recorded (which is absurd since of course you could simply use a notepad and hand copy in what you want, but this is human nature and suspicion, we're talking about).

I understand the US Secret Service has analyzed lab notebooks in some major disputes.

(To the best of my knowledge nobody has ever looked at my notebooks after I was done with them).

It does seem like the best solution, in a way. But the higher up people still seem to think it's incorrect and ugly. It's definitely ugly, but my handwriting is completely illegible anyway, so no fixing that.

I have found these indispensable: https://store.artlebedev.com/office/stationary/millimetrus2/