Car manufacture 1st cars in one box. Trucks in another.
My spreadsheet is a spiral not book. Number boxes by letter F-1 = Ford cars Box 1. So when I look for a model i can check by brand 1st and not have to go through a big pile of boxes to find the Model I need.
I have puchrased the large index cards to switch over because the stash has grown. I grabed a recipe box to store them in. Any way to save time when hunting stops us from buying another because you just can't find it. The way you sort is up to you, but I feel keeping same types together is faster to search. Streetrods and stock drivers in thier own box when possible.
Kit number and brand of kit on the card alsp helps.