Has anyone tried the “invest every dollar” method for a long period of time and if so, how has it worked out for you?

This method is where you invest every dollar outside of your month to month bills into the S&P 500. Also maybe keeping 3-6 months of expenses aside as well, but nothing beyond that.

Essentially using the S&P 500 as your lifetime “savings account.” You forgo paying off your mortgage early, and only keep enough cash for month to month bills and short term expenses. Every extra dollar goes into the S&P 500, no other allocations. Big expense comes up? Either sell some shares if the market is up, if the market is down, take out some margin.

Seems like it would be lucrative, but would take a lot of guts.