"Idiot light" vs. Oil Pressure Gauge

I'll come back and comment further from recent experience. Modern filters do indeed have a bypass valve, but I've first hand experience that they don't work well or at all. I recently had a big block Chevy I built wipe several cam lobes (Thanks Comp) and it stopped the filter up and lost oil pressure. It was a WIX filter, too. So the bypass valve failed. I'm actually kinda glad it did. It probably saved the rest of the engine, because I was watching the gauge when it fell and killed the ignition.