My first PPT presentation was a single graph on a slide with large axis titles and labels. It summarized the output of a model we were building.
Manager wanted to add a ton of content that they felt would be helpful. I said sure, and added it to an appendix with arrows, callouts, additional definitions, etc.
I then presented it to the CxO group -- we only discussed that first slide. I emailed the deck, and got comments back saying that the appendix was confusing but they loved how simple and clear the single non-appendix slide was.
I've always tried to follow the 4x4 rule: no more than 4 lines, and no more than 4 words per line. I've found icons and occasionally diagrams can be helpful in explaining more abstract concepts. Also, slide notes are used liberally.
One place I worked was veeery similar to what you describe here. PPT was considered docs of record since no one wanted to make formal memos and have those enter the control system. My approach had friction, since I would be extremely concise and direct people to the slide notes if they had questions. In this org, people were notorious for lifting slides from others decks for their own presentations (hence I would distribute as PDF to discourage this) since people would not field questions those slides might raise.
