I used to always make pictures and I still do make a fair amount but it tends to be higher-level system or data/process flows.

When it comes to getting a handle on complexity, I find it better to list all the dimensions of variability and decide how they relate. Any before-and-after (but not necessarily during) invariants are gold. Then I can choose where/when to deal with which dimension(s) while other parts are agnostic to those.