Actually, as a woman who had a very heavy flow as a teen in the low ’90s, there absolutely are very thin options for even the heaviest of flows. Always makes “overnight” pads that almost always prevented any leaks or spillover. The ones available now are even faster to absorb, but 22 years ago, they were still pretty good. I would sleep with dark towels to save my sheets, but aside from actual overnight use, and sudden surges from standing up after hours of sitting, they were pretty effective. Thicker ones actually make the risk of leaks onto clothes more likely, in my personal experience.
+1 for Thoroughly Modern Millie .gif!