If you’re going to use a USB with CDJ’s then RekordBox is the way forward. Organise all your folders and playlists in RekordBox, plug in your USB, drag over the playlists/folders that you want on the USB, done.
I carry two usb’s. One with rekordbox analyzed tracks exported from my playlist on itunes. Another with just plain folders of the playlist incase its an older cdj, or something that doesn’t use rekordbox.
the usb’s that i carry are only for backup, however they are organised as exact mirrors of my serato crates, incase my laptop goes down, i will have enough to worry about, and hunting for tunes needs to be bottom of the list.