If something got a look inside your book, everything is compromised. At least by changing to another random gibberish password, an attacker would not get back in (in contrast to someone that increments a number, for example), but how much damage can something do in that time before you notice? How long do you think it takes a skilled attacker to install a backdoor (the answer is definitely less than 44 days)?
This is the second major problem with password rotation: it is false security. If credentials are compromised, immediately change them: don't wait 45 or 90 days.
If they're not compromised, changing them is basically pointless, because humans are going to human and either have an incrementing number, predictable pattern, or actual complex, random, unrelated passwords ... that they then write down.