Sometimes when I’m writing mysteries I find that I lose track of who knows what when and I find it useful to write out a simple plot ladder based on character. Do you guys ever do that? I find that if I temporally line up one character’s plot ladder with another’s I can more easily ‘see’ the order of the scenes and revelations.

I’ve never personally tried that. Usually my outline and my own memory does that for me. Though one day I might try, especially if I have a really complicated story.
Yeah, I don’t use it all the time, but for this casebook I found that I had to keep reminding myself where Whitaker was while Portia was away, and what happened to Gruner before he met Whitaker etc. This way I can see at a glance (while I shift my scenes around in my document).