I love notebooks. I have a stack of them. I also could never find anything in them, which made the love a one-way relationship.
Six months ago I switched to one text file with a date heading per day. I can search it. I can grep it. I can find the line I wrote on a train in March and I could not before.
I still keep a notebook for meetings. The text file is for me. The split has been quietly, surprisingly good.